- Hydroperoxide and peroxynitrite reductase activity of poplar thioredoxin-dependent glutathione peroxidase 5: Kinetics, catalytic mechanism and oxidative inactivation
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Gpxs (glutathione peroxidases) constitute a family of peroxidases, including selenocysteine- or cysteine-containing isoforms (SeCys-Gpx or Cys-Gpx), which are regenerated by glutathione or Trxs (thioredoxins) respectively. In the present paper we show new data concerning the substrates of poplar Gpx5 and the residues involved in its catalytic mechanism. The present study establishes the capacity of this Cys-Gpx to reduce peroxynitrite with a catalytic efficiency of 106 M-1·s-1. In PtGpx5 (poplar Gpx5; Pt is Populus trichocarpa), Glu79, which replaces the glutamine residue usually found in the Gpx catalytic tetrad, is likely to be involved in substrate selectivity. Although the redox midpoint potential of the Cys44-Cys92 disulfide bond and the pKa of Cys44 are not modified in the E79Q variant, it exhibited significantly improved kinetic parameters (Kperoxide and kcat) with tert-butyl hydroperoxide. The characterization of the monomeric Y151R variant demonstrated that PtGpx5 is not an obligate homodimer. Also, we show that the conserved Phe90 is important for Trx recognition and that Trx-mediated recycling of PtGpx5 occurs via the formation of a transient disulfide bond between the Trx catalytic cysteine residue and the Gpx5 resolving cysteine residue. Finally, we demonstrate that the conformational changes observed during the transition from the reduced to the oxidized form of PtGpx5 are primarily determined by the oxidation of the peroxidatic cysteine into sulfenic acid. Also, MS analysis of in-vitro-oxidized PtGpx5 demonstrated that the peroxidatic cysteine residue can be over-oxidized into sulfinic or sulfonic acids. This suggests that some isoforms could have dual functions potentially acting as hydrogen-peroxide- and peroxynitrite- scavenging systems and/or as mediators of peroxide signalling as proposed for 2-Cys peroxiredoxins. The Authors Journal compilation
- Selles, Benjamin,Hugo, Martin,Trujillo, Madia,Srivastava, Vaibhav,Wingsle, Gunnar,Jacquot, Jean-Pierre,Radi, Rafael,Rouhier, Nicolas
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- TiO2 photocatalytic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O: Incorporation effect of nanometer-sized Ag particles
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A highly endothermic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O selectively proceeds using TiO2 as a photocatalyst, being significantly enhanced upon incorporation of nanometer-sized Ag particles on TiO2
- Tada, Hiroaki,Teranishi, Kazuaki,Inubushi, Yo-Ichi,Ito, Seishiro
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- In situ formation of protein-polymer conjugates through reversible addition fragmentation chain transfer polymerization
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(Figure Presented) A good place for rafting: Bovine serum albumin (BSA) was site-specifically modified with a reversible addition fragmentation chain transfer (RAFT) agent and used in γ-radiation-initiated polymerization of oligo(ethylene glycol) acrylate. Well-defined polymer chains were formed at the RAFT agent conjugation site of BSA leading to the generation of BSA-polymer conjugates in situ.
- Liu, Jingquan,Bulmus, Volga,Herlambang, David L.,Barner-Kowollik, Christopher,Stenzel, Martina H.,Davis, Thomas P.
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- Reduction-sensitive tioguanine prodrug micelles
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Colloidal drug and prodrug conjugates have unique targeting characteristics for tumor vasculature from the blood and for the lymphatics draining a tissue injection site. Tioguanine and tioguanine-generating prodrugs have been investigated as anticancer and immunosuppressive agents, including use in cancer immunotherapy. Recently we developed block copolymers of poly(ethylene glycol)-bl-poly(propylene sulfide) that self-assemble in aqueous solutions to form micellar structures. Since the polymers carry a free terminal thiol group resulting from the ring-opening polymerization of the propylene sulfide monomer, we sought to prepare prodrug block copolymers with tioguanine linked by a reduction-sensitive disulfide bond. The synthesis involved a disulfide exchange between the oxidized form of tioguanine and the polymer. Spectroscopic data is presented to support the proposed reaction. The polymers self-assembled when dispersed in water to form tioguanine prodrug micelles with a size range between 18 and 40 nm that released tioguanine in response to cysteine and serum as shown spectroscopically. In comparison with a poly(ethylene glycol) prodrug polymer, we show that the rate of tioguanine release can be controlled by changing the poly(propylene sulfide) block length and that the tioguanine remains bioactive with cultured cells.
- Van Der Vlies, André J.,Hasegawa, Urara,Hubbell, Jeffrey A.
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- Phosphodisulfide bond: A new linker for the oligonucleotide conjugation
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Oligonucleotide thiophosphates react with 2-pyridyl-disulfide derivatives to give phosphodisulfide which can, upon reduction, be easily cleaved to give the starting oligonucleotide with a terminal thiophosphate group.
- Chassignol, Marcel,Thuong, Nguyen T.
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- Size-dependence of Fermi energy of gold nanoparticles loaded on titanium(iv) dioxide at photostationary state
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TiO2 particle-supported Au nanoparticles (NPs) with varying sizes and good contact (Au/TiO2) were prepared under a constant loading amount by the deposition-precipitation method. The Fermi energy of Au NPs loaded on TiO2 a
- Kiyonaga, Tomokazu,Fujii, Masashi,Akita, Tomoki,Kobayashi, Hisayoshi,Tada, Hiroaki
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- A synthetic strategy using Witkop's pyrroloindole for (-)-debromoflustramine B, (+)-ent-debromoflustramine B and (+)-ent-debromoflustramide B
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While prenylation of (-)-Witkop's pyrroloindole (2), secured from l-tryptophan under standard N-alkylation conditions, led to a ca. 1:1 diastereoisomeric mixture of two C3a-alkylated indolenines 3 and 4, use of phase-transfer conditions altered this to ca. 1:2. Reduction followed by N-prenylation of the resulting secondary amines gave C,N-dialkylated products. The derived separable diastereoisomeric (-)- and (+)-Barton esters 19a and 19b were then converted into (-)-debromoflustramine B and (+)-ent-debromoflustramine B, respectively. A novel reaction involving oxygen and the carbanion derived from Barton ester 19b led to (+)-ent-debromoflustramide B. Treatment of N8-prenylated Witkop's pyrroloindole 5 with Lewis acid (BF3·Et2O) uncovered a new clean intramolecular cyclisation involving the prenyl unit.
- Cardoso, A. Sofia P.,Marques, M. Manuel B.,Srinivasan, Natarajan,Prabhakar, Sundaresan,Lobo, Ana M.
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- Mass spectrometry-based assay for the rapid detection of thiol-containing natural products
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Natural products are privileged scaffolds due to their high propensity to possess bioactivity. To expedite discovery of thiol-containing compounds, we devised a selective solid-supported reagent for their immobilization, followed by cleavage of a photocleavable linker to yield stable natural product conjugates for direct detection by mass spectrometry. Importantly, the natural products can also be tracelessly released to yield the native structures for chemical and biological evaluation.
- Capehart, Stacy L.,Carlson, Erin E.
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- 2-Pyridinethiol/2-pyridinethione tautomeric equilibrium. A comparative experimental and computational study
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The gas phase and solvent dependent preference of the tautomerization between 2-pyridinethiol (2SH) and 2-pyridinethione (2S) has been assessed using variable temperature Fourier transform infrared (FTIR) experiments, as well as ab initio and density functional theory computations. No spectroscopic evidence (vS-H stretch) for 2SH was observed in toluene, C6D6, heptane, or methylene chloride solutions. Although, Cs 2SH is 2.61 kcal/mol more stable than Cs 2S (CCSD(T)/cc-pVTZ//B3LYP/6-311+G(3df,2p)+ZPE), cyclohexane solvent-field relative energies (IPCM-MP2/6-311+G-(3df,2p)) favor 2S by 1.96 kcal/mol. This is in accord with the FTIR observations and in quantitative agreement with the -2.6 kcal/mol solution (toluene or C6D6) calorimetric enthalpy for the 2S/2SH tautomerization favoring the thione. As the intramolecular transition state for the 2S, 2SH tautomerization (2TS*) lies 25 (CBS-Q) to 30 kcal/mol (CCSD/cc-pVTZ) higher in energy than either tautomer, tautomerization probably occurs in the hydrogen bonded dimer. The B3LYP/6-311+G-(3df,2p) optimized C2 2SH dimer is 10.23 kcal/mol + ZPE higher in energy than the C2h 2S dimer and is only 2.95 kcal/mol + ZPE lower in energy than the C2 2TS* dimer transition state. Dimerization equilibrium measurements (FTIR, C6D6) over the temperature range 22-63°C agree: Keq298 = 165 ± 40 M-I, ΔH = -7.0 ± 0.7 kcal/mol, and ΔS = -13.4 ± 3.0 cal/(mol deg). The difference between experimental and B3LYP/6-311+G(3df,2p) [-34.62 cal/(mol deg)] entropy changes is due to solvent effects. The B3LYP/6-311+G(3df,2p) nucleus independent chemical shifts (NICS) are -8.8 and -3.5 ppm 1 A above the 2SH and 2S ring centers, respectively, and the thiol is aromatic. Although the thione is not aromatic, it is stabilized by the thioamide resonance. In solvent, the large 2S dipole, 2-3 times greater than 2SH, favors the thione tautomer and, in conclusion, 2S is thermodynamically more stable than 2SH in solution.
- Moran, Damian,Sukcharoenphon, Kengkaj,Puchta, Ralph,Schaefer III, Henry F.,Schleyer, Paul V.R.,Hoff, Carl D.
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- The effect of nanometre-sized Au particle loading on TiO2 photocatalysed reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O
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TiO2 photocatalysed reduction of bis(2-dipyridyl)disulfide (RSSR) to 2-mercaptopyridine by H2O is enhanced significantly by incorporation of nanometre-sized Au particles. The rate is strongly dependent on the amount of Au loaded (x w
- Tada,Suzuki,Yoneda,Ito,Kobayashi
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- Highly uniform self-assembled monolayers of silver nanospheres for the sensitive and quantitative detection of glutathione by SERS
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The homeostasis and imbalance of glutathione (GSH), an important antioxidant in organisms, are one of the key signals that reflect the health of organisms. In this paper, a novel SERS sensing platform based on Ag film@Si that self-assembled using silver nanospheres was proposed, which was used for the highly sensitive and selective detection of GSH. With the aid of an oil/water/oil three-phase system, the nano-silver film was self-assembled and finally deposited on silicon wafers. The heterobifunctional crosslinking agentN-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), which contains pyridine rings and disulfide bonds, was involved in the exchange reaction between the sulfhydryl groups and disulfide bonds. With the addition of GSH, the breakage of disulfide bonds was promoted, thereby enhancing the SERS signal of SPDP. GSH can be detected sensitively by detecting the changes in the SPDP signal. The detection limit of GSH is 10 nM, and the method is still highly stable when the external environment is serum or other more complex environments.
- Chen, Yi,Huang, Feixiang,Jiang, Cailing,Jiang, Li
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- Integrated preparation method of 2-mercaptopyridine and 2, 2 '-pyridinium sulfide
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The invention discloses an integrated preparation method of 2-mercaptopyridine and 2, 2 '-pyridinium sulfide, which comprises the steps of adding sulfur, sodium sulfide and a composite catalyst into water serving as a solvent, and uniformly stirring under a heating condition until the sulfur, the sodium sulfide and the composite catalyst are all dissolved; then adding 2-halogenated pyridine, and reacting for 20-30 hours at a reflux temperature, wherein the composite catalytic system is prepared by adding a cocatalyst with the same weight as cesium acetate into cesium acetate; after the reaction is finished, cooling the reaction liquid to the room temperature, then conducting extraction to respectively obtain extraction liquid and raffinate reaction liquid, and enabling the extraction liquid and the raffinate reaction liquid to be subjected to aftertreatment respectively to obtain 2, 2 '-pyridinium sulfide and 2-mercaptopyridine. The method can obtain two main products at the same time, and generation of by-products is reduced.
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Paragraph 0037-0045
(2021/09/15)
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- Washington Red (WR) dyes and their imaging applications
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Near-infrared (NIR) fluorescent dyes with optimum photophysical properties are highly useful for bioimaging in living systems, but such dyes are still rare. Recently, our laboratory developed a unique class of NIR fluorescent dyes with high quantum yields and large Stokes shifts. These dyes, named as Washington Red (WR), were found to be useful scaffolds to develop NIR fluorescent imaging probes upon easy modifications on their phenolic hydroxyl group. In this chapter, we provide a comprehensive summary of this work, including the design and synthesis of WR dyes, their photophysical properties studies, and applications in developing NIR probes to image H2S in cells. The detailed experimental protocols are described.
- Chen, Wei,Xian, Ming
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p. 149 - 163
(2020/06/08)
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- Promoting Effect of Crystal Water Leading to Catalyst-Free Synthesis of Heteroaryl Thioether from Heteroaryl Chloride, Sodium Thiosulfate Pentahydrate, and Alcohol
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It is observed the crystal water in sodium thiosulfate pentahydrate (Na2S2O3·5H2O) can promote its multicomponent reaction with heteroaryl chlorides and alcohols, providing a facile, green, and specific synthesis of unsymmetrical heteroaryl thioethers via one-step formation of two C-S bonds under catalyst-, additive-, and solvent-free conditions. Mechanistic studies suggest that the crystal water in Na2S2O3·5H2O is crucial in generating the key thiol intermediates and byproduct NaHSO4, which then catalyzes the dehydrative substitution of alcohols with thiols to afford thioethers.
- Ma, Xiantao,Yu, Jing,Yan, Ran,Yan, Mengli,Xu, Qing
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supporting information
p. 11294 - 11300
(2019/09/12)
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- Pyridinethiol-Assisted Dissolution of Elemental Gold in Organic Solutions
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Dissolution of elemental gold in organic solutions is a contemporary approach to lower the environmental burden associated with gold recycling. Herein, we describe fundamental studies on a highly efficient method for the dissolution of elemental Au that is based on DMF solutions containing pyridine-4-thiol (4-PSH) as a reactive ligand and hydrogen peroxide as an oxidant. Dissolution of Au proceeds through several elementary steps: isomerization of 4-PSH to pyridine-4-thione (4-PS), coordination with Au0, and then oxidation of the Au0 thione species to AuI simultaneously with oxidation of free pyridine thione to elemental sulfur and further to sulfuric acid. The final dissolution product is a AuI complex bearing two 4-PS ligands and SO42? as a counterion. The ligand is crucial as it assists the oxidation process and stabilizes and solubilizes the formed Au cations.
- R?is?nen, Minna,Heli?vaara, Eeva,Al-Qaisi, Feda'a,Muuronen, Mikko,Eronen, Aleksi,Liljeqvist, Henri,Nieger, Martin,Kemell, Marianna,Moslova, Karina,H?m?l?inen, Jani,Lagerblom, Kalle,Repo, Timo
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supporting information
p. 17104 - 17109
(2018/12/04)
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- Hydropersulfides: H-Atom Transfer Agents Par Excellence
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Hydropersulfides (RSSH) are formed endogenously via the reaction of the gaseous biotransmitter hydrogen sulfide (H2S) and disulfides (RSSR) and/or sulfenic acids (RSOH). RSSH have been investigated for their ability to store H2S in vivo and as a line of defense against oxidative stress, from which it is clear that RSSH are much more reactive to two-electron oxidants than thiols. Herein we describe the results of our investigations into the H-atom transfer chemistry of RSSH, contrasting it with the well-known H-atom transfer chemistry of thiols. In fact, RSSH are excellent H-atom donors to alkyl (k ~ 5 × 108 M-1 s-1), alkoxyl (k ~ 1 × 109 M-1 s-1), peroxyl (k ~ 2 × 106 M-1 s-1), and thiyl (k > 1 × 1010 M-1 s-1) radicals, besting thiols by as little as 1 order and as much as 4 orders of magnitude. The inherently high reactivity of RSSH to H-atom transfer is based largely on thermodynamic factors; the weak RSS-H bond dissociation enthalpy (~70 kcal/mol) and the associated high stability of the perthiyl radical make the foregoing reactions exothermic by 15-34 kcal/mol. Of particular relevance in the context of oxidative stress is the reactivity of RSSH to peroxyl radicals, where favorable thermodynamics are bolstered by a secondary orbital interaction in the transition state of the formal H-atom transfer that drives the inherent reactivity of RSSH to match that of α-tocopherol (α-TOH), nature's premier radical-trapping antioxidant. Significantly, the reactivity of RSSH eclipses that of α-TOH in H-bond-accepting media because of their low H-bond acidity (α2H ~ 0.1). This affords RSSH a unique versatility compared to other highly reactive radical-trapping antioxidants (e.g., phenols, diarylamines, hydroxylamines, sulfenic acids), which tend to have high H-bond acidities. Moreover, the perthiyl radicals that result are highly persistent under autoxidation conditions and undergo very rapid dimerization (k = 5 × 109 M-1 s-1) in lieu of reacting with O2 or autoxidizable substrates.
- Chauvin, Jean-Philippe R.,Griesser, Markus,Pratt, Derek A.
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supporting information
p. 6484 - 6493
(2017/09/12)
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- Efficient Generation of C–S Bonds via a By-Product-Promoted Selective Coupling of Alcohols, Organic Halides, and Thiourea
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A metal- and base-free three-component coupling of alcohols, heteroaryl halides, and thiourea has been developed for direct and selective synthesis of heteroaryl thioethers. This method can be easily scaled up to the gram scale and extended to dialkyl thioethers, heteroaryl selenides, benzothiazoles, and some antimycobacterially-active thioethers. Mechanistic studies revealed that a by-product-promoted in situ C–O activation of alcohols to more reactive alkyl halides and slow release of the thiol and alkyl halide intermediates are the key to the high selectivity and success of the reaction. (Figure presented.).
- Ma, Xiantao,Yu, Lei,Su, Chenliang,Yang, Yaqi,Li, Huan,Xu, Qing
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supporting information
p. 1649 - 1655
(2017/05/29)
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- Copper-Catalyzed Direct Synthesis of Aryl Thiols from Aryl Iodides Using Sodium Sulfide Aided by Catalytic 1,2-Ethanedithiol
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A copper-catalyzed direct and effective synthesis of aryl thiols from aryl iodides using readily available Na 2 S·9H 2 O and 1,2-ethanedithiol was described. A variety of aryl thiols were readily obtained in yields of 76-99%. In this protocol, Na 2 S·9H 2 O was used as ultimate sulfur source, and 1,2-ethanedithiol functioned as an indispensable catalytic reagent.
- Xue, Hongyu,Jing, Bing,Liu, Shasha,Chae, Junghyun,Liu, Yajun
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p. 2272 - 2276
(2017/10/06)
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- Photoinduced heterodisulfide metathesis for reagent-free synthesis of polymer nanoparticles
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Reagent-free synthetic methods are of great interest because of their simplicity and implications in green chemistry. We have taken advantage of photoinduced heterodisulfide metathesis to generate crosslinked polymer nanoparticles. The method of development and the mechanistic basis for the synthetic approach are outlined in this communication.
- Li, Longyu,Song, Cunfeng,Jennings, Matthew,Thayumanavan
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p. 1425 - 1428
(2015/08/03)
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- Deoxygenation of amine N-oxides using gold nanoparticles supported on carbon nanotubes
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Deoxygenation of a variety of aromatic and aliphatic amine N-oxides has been carried out in excellent yield using dimethylphenylsilane as the reducing agent under the catalytic influence of a carbon nanotube-gold nanohybrid at room temperature. Low catalyst loading, good TON and TOF values, and recyclability of the catalyst are some of the salient features of our methodology.
- Donck, Simon,Gravel, Edmond,Shah, Nimesh,Jawale, Dhanaji V.,Doris, Eric,Namboothiri, Irishi N. N.
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p. 50865 - 50868
(2015/06/25)
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- A THIONATION PROCESS AND A THIONATING AGENT
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A process for transforming a group >C=O (I) in a compound into a group >C=S (II) or into a tautomeric form of group (II) in a reaction giving a thionated reaction product, by use of crystalline P2S5·2 C5H5N as a thionating agent. A thionating agent which is crystalline P2S5·2 C5H5N
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Page/Page column 13
(2012/08/27)
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- A thionation process and a thionating agent
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A process for transforming a group >C=O (I) in a compound into a group >C=S (II) or into a tautomeric form of group (II) in a reaction giving a thionated reaction product, by use of crystalline P2S5·2 C5H5N as a thionating agent. A thionating agent which is crystalline P2S5·2 C5H5N.
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Page/Page column 9
(2012/08/14)
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- Micelles based on gold-glycopolymer complexes as new chemotherapy drug delivery agents
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Polymeric versions of deacetylated auranofin, a gold complex with a sugar ligand, were prepared by post-modifying RAFT glycopolymers. Micellisation of a block copolymer containing pendant Au(i) units produced nanoparticles with an increased anti-proliferative effect against OVCAR-3 human ovarian carcinoma cells.
- Pearson, Samuel,Scarano, Wei,Stenzel, Martina H.
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supporting information; experimental part
p. 4695 - 4697
(2012/06/01)
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- Targeted and armed oncolytic adenovirus via chemoselective modification
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Oncolytic adenoviruses (Ads) are an emerging alternative therapy for cancer; however, clinical trial have not yet demonstrated sufficient efficacy. When oncolytic Ads are used in combination with taxoids a synergistic increase in both cytotoxicity and viral replication is observed. In order to generate a next generation oncolytic adenovirus, virion were physically conjugated to a highly potent taxoid, SB-T-1214, and a folate targeting motif. Conjugation was enabled via the metabolic incorporation of non-canonical monosaccharides (O-GlcNAz) and amino acids (homopropargylglycine), which served as sites for chemoselective modification.
- Banerjee, Partha S.,Zuniga, Edison S.,Ojima, Iwao,Carrico, Isaac S.
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p. 4985 - 4988
(2011/10/09)
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- Reduction of amine N-oxides by diboron reagents
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Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis- (pinacolato)- and in some cases bis(catecholato)diboron [(pinB)2 and (catB)2, respectively]. Reductions occur upon simply mixing the amine N oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N-dioxide of (S)-(-)-nicotine. Because it was observed that (pinB)2 was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)2, triethylborane reduced alkylamino-N oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)2 has been probed by 1H and 11B NMR. (Figure presented) ; 2011 American Chemical Society.
- Kokatla, Hari Prasad,Thomson, Paul F.,Bae, Suyeal,Doddi, Venkata Ramana,Lakshman, Mahesh K.
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experimental part
p. 7842 - 7848
(2011/12/01)
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- Thionations using a P4S10-pyridine complex in solvents such as acetonitrile and dimethyl sulfone
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Tetraphosphorus decasulfide (P4S10) in pyridine has been used as a thionating agent for a long period of time. The moisture-sensitive reagent has now been isolated in crystalline form, and the detailed structure has been determined by X-ray crystallography. The thionating power of this storable reagent has been studied and transferred to solvents such as acetonitrile in which it has proven to be synthetically useful and exceptionally selective. Its properties have been compared with the so-called Lawesson reagent (LR). Particularly interesting are the results from thionations at relatively high temperatures (165 °C) in dimethyl sulfone as solvent. Under these conditions, for instance, acridone and 3-acetylindole could quickly be transformed to the corresponding thionated derivatives. Glycylglycine similarly gave piperazinedithione. At these temperatures, LR is inefficient due to rapid decomposition. The thionated products are generally cleaner and more easy to obtain because in the crystalline reagent, impurities which invariably are present in the conventional reagents, P4S 10 in pyridine or LR, have been removed. 2011 American Chemical Society.
- Bergman, Jan,Pettersson, Birgitta,Hasimbegovic, Vedran,Svensson, Per H.
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experimental part
p. 1546 - 1553
(2011/06/11)
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- NOVEL AROMATIC COMPOUND AND POLYARYLENE COPOLYMER HAVING NITROGEN-CONTAINING HETEROCYCLE INCLUDING SULFONIC ACID GROUP IN SIDE CHAIN
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Provided is a solid polymer electrolyte having increased heat resistance and high proton conductivity and a proton conductive membrane composed of the electrolyte. Also provided is a copolymer having a sulfonic acid group. The copolymer includes a repeating unit represented by Formula (1): (in the formula, Y denotes at least one kind of structure selected from the group consisting of —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), and —C(CF3)2—; W denotes at least one kind of structure selected from the group consisting of a direct bond, —CO—, —SO2—, —SO—, —CONH—, —COO—, —(CF2)l— (l is an integer of 1 to 10), —C(CF3)2—, —O—, and —S—; Z denotes a direct bond or at least one kind of structure selected from the group consisting of —(CH2)l—(l is an integer of 1 to 10), —C(CH3)2—, —O—, —S—, —CO—, and —SO2—; R30 denotes a nitrogen-containing aromatic ring having a substituent represented by —SO3H, —O(CH2)hSO3H, or —O(CF2)hSO3H (h is an integer of 1 to 12); p is an integer of 0 to 10; q is an integer of 0 to 10; r is an integer of 1 to 5; and k is an integer of 0 to 4).
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- Exofacial protein thiols as a route for the internalization of Gd(III)-based complexes for magnetic resonance imaging cell labeling
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Four novel MRI Gd(III)-based probes have been synthesized and evaluated for their labeling properties on cultured cell lines K562, C6, and B16. The labeling strategy relies upon the fact that cells display a large number of reactive exofacial protein thio
- Digilio, Giuseppe,Menchise, Valeria,Gianolio, Eliana,Catanzaro, Valeria,Carrera, Carla,Napolitano, Roberta,Fedeli, Franco,Aime, Silvio
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experimental part
p. 4877 - 4890
(2010/10/19)
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- Nanoscale organization of thiol and arylsulfonic acid on silica leads to a highly active and selective bifunctional, heterogeneous catalyst
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Ordered mesoporous silicas functionalized with alkylsulfonic acid and thiol group pairs have been shown to catalyze the synthesis of bisphenols from the condensation of phenol and various ketones, with activity and selectivity highly dependent on the distance between the acid and thiol. Here, a new route to thiol/sulfonic acid paired catalysts is reported. A bis-silane precursor molecule containing both a disulfide and a sulfonate ester bond is grafted onto the surface of ordered mesoporous silica, SBA-15, followed by simultaneous disulfide reduction and sulfonate ester hydrolysis. The resulting catalyst, containing organized pairs of arylsulfonic acid and thiol groups, is significantly more active than the alkylsulfonic acid/thiol paired catalyst in the synthesis of bisphenol A and Z, and this increase in activity does not lead to a loss of regioselectivity. The paired catalyst has activity similar to that of a randomly bifunctionalized arylsulfonic acid/thiol catalyst in the bisphenol A reaction but exhibits greater activity and selectivity than the randomly bifunctionalized catalyst in the bisphenol Z reaction.
- Margelefsky, Eric L.,Bendjeriou, Anissa,Zeidan, Ryan K.,Dufaud, Veronique,Davis, Mark E.
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experimental part
p. 13442 - 13449
(2009/02/06)
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- Novel N,S-phenacyl protecting group and its application for peptide synthesis
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The phenacyl group can be introduced onto amino and thio groups by N,S-alkylation reactions. Conversely, these groups are removed rapidly by employing magnesium in acetic acid. This protecting group was successfully applied to a short peptide synthesis of Boc-L-Cys-Gly-OMe. Georg Thieme Verlag Stuttgart.
- Tang, Guo,Ji, Tao,Hu, An-Fu,Zhao, Yu-Fen
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experimental part
p. 1907 - 1909
(2009/04/11)
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- Pharmaceutical composition containing liposomes for treating cancer
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The present invention provides liposome-containing drug administration carriers that have improved residence time in the blood and improved migration into tumor cells as compared with conventional ones and that have reduced accumulation in the heart, and
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Page/Page column 10
(2008/06/13)
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- Heteroaryl thioglycosides, a new class of substrates for glycosidases
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We have found that heteroaryl thioglycosides are useful substrates of β-glucosidase from almond and can act as a new class of donors in transglycosylation reaction.
- Niemiec-Cyganek,Szeja
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p. 969 - 973
(2007/10/03)
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- Cosmetic composition forming a tackifying coating comprising a polymer with a non-silicone skeleton and reactive functional groups
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Cosmetic compositions, comprising at least one polymer with a non-silicone skeleton, comprising at least two reactive chemical functional groups, that is capable of forming a tackifying coating on the hair, a cosmetic process comprising the application of the composition to the hair, and also its use for producing a tackifying coating on the hair.
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- Cosmetic composition forming a soft coating comprising a polymer having a non-silicone backbone and reactive functional groups
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Nontacky cosmetic compositions, such as hair compositions, comprising at least one polymer having a non-silicone backbone, comprising at least two reactive chemical functional groups, capable of forming a soft coating on hair, a cosmetic process comprising the application of this composition to hair and its use for producing a soft coating on hair.
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- Cosmetic composition forming a rigid coat, comprising a polymer with a non-silicone skeleton and containing reactive functional groups
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Cosmetic compositions, such as hair compositions, comprising at least one polymer with a non-silicone skeleton, comprising at least two reactive chemical functional groups, which are capable of forming a rigid coat on the hair, a cosmetic process comprising the application of this composition onto the hair, and its use for producing a rigid coat on the hair.
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- Synthesis of pyridothietone by flash vacuum pyrolysis of 2-mercaptonicotinic acid
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The temperature dependence of products formed from flash vacuum pyrolysis (FVP) of 2-mercaptonicotinic acid 4 has been studied. FVP of 4 at 550°C and ca. 1×10-2 torr gave pyridothietone 3b and a trimer 5 as the major products. At higher temperature (800°C), FVP of 4 gave 2-mercaptopyridine 6 as the major product and 2,2′-dipyridyl disulphide 7 as the minor one.
- Chou, Chin-Hsing,Chiu, Shao-Jung,Liu, Wei-Min
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p. 5285 - 5286
(2007/10/03)
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- Instant degradation of plastics into soluble non-toxic products
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The present invention describes novel, cost-effective and rapid processes suitable for degradation and recycling of specially designed plastics, which are defined as instantly degradable synthetic polymeric plastics having the characteristics and properties of conventional forms of plastics. These novel plastic products are made from a variety of compositions of polymers and their compatible nontoxic modifiers. The resulting novel instant degradable plastic products retain latent solubility properties which are triggered upon mild chemical processes of the present invention, thus enabling cost effective and facile recycling of plastic refuge.
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- A new synthesis of (-)-debromoflustramine B, (+)-ent-debromoflustramine B and (+)-debromoflustramide B
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The first synthesis of (-)-debromoflustramine B is reported. Appropriate structural modifications of an optically pure Barton ester, obtained in five steps from N-acetyl-L-tryptophan methyl ester, lead to the alkaloid.
- Cardoso,Srinivasan, Natarajan,Lobo, Ana M,Prabhakar, Sundaresan
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p. 6663 - 6666
(2007/10/03)
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- A general palladium-catalysed synthesis of aromatic and heteroaromatic thioethers
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Thioethers can be efficiently prepared via palladium-catalysed cross-coupling of arene- or heteroarene thiols with arene- or heteroarene iodides. A simple, cheap and robust catalytic system is described that couples a broad range of electron-deficient as well as electron-rich substrates in high yield.
- Schopfer, Ulrich,Schlapbach, Achim
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p. 3069 - 3073
(2007/10/03)
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- Precious metal composition
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Gold thiolates of formula AuSR'' or a salt thereof, in which R'' is such that HSR'' represents: 4,6-dihydroxy-2-mercaptopyrimidine; N-(2-mercaptoacetyl)glycine; N-(3-mercaptopropionyl)glycine; and N-(2-mercaptopropionyl)glycine. The invention provides also processes for preparing novel gold thiolates.
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- A rapid and efficient cleavage of organic disulfides to mercaptans using ZrCl4/NaBH4
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A practical and cheaper reagent system ZrCl/NaBH4 is used for the reductive cleavage of organic disulfides to mercaptans under mild conditions, in excellent yields.
- Purushothama Chayr,Rajaram,Iyengar
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p. 3905 - 3911
(2007/10/03)
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- Macroporous p-type silicon Fabry-Perot layers. Fabrication, characterization, and applications in biosensing
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We present in this paper that porous silicon can be used as a large surface area matrix as well as the transducer of biomolecular interactions. We report the fabrication of heavily doped p-type porous silicon with pore diameters that can be tuned, depending on the etching condition, from approximately 5 to 1200 nm. The structure and porosity of the matrixes were characterized by scanning force microscopy (SFM) and scanning electron microscopy (SEM), Brunnauer-Emmett-Teller nitrogen adsorption isotherms, and reflectance interference spectroscopy. The thin porous silicon layers are transparent to the visible region of the reflectance spectra due to their high porosity (80-90%) and are smooth enough to produce Fabry-Perot fringe patterns upon white light illumination. Porous silicon matrixes were modified by ozone oxidation, functionalized in the presence of (2- pyridyldithiopropionamidobutyl)dimethylmethoxysilane, reduced to unmask the sulfhydryl functionalities, and coupled to biotin through a disulfide-bond- forming reaction. Such functionalized matrixes display considerable stability against oxidation and corrosion in aqueous media and were used to evaluate the utility of porous silicon in biosensing. The streptavidin-biotin interactions on the surface of porous silicon could be monitored by the changes in the effective optical thickness calculated from the observed shifts in the Fabry-Perot fringe pattern caused by the change in the refractive index of the medium upon protein-ligand binding. Porous silicon thus combines the properties of a mechanically and chemically stable high surface area matrix with the function of an optical transducer and as such may find utility in the fabrication of biosensor devices.
- Janshoff, Andreas,Dancil, Keiki-Pua S.,Steinem, Claudia,Greiner, Douglas P.,Lin, Victor S.-Y.,Gurtner, Christian,Motesharei, Kianoush,Sailor, Michael J.,Reza Ghadiri
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p. 12108 - 12116
(2007/10/03)
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- Kinetics and mechanism of the nitrosation of 2-mercaptopyridine [pyridine-2(1H)-thione]
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2-Mercaptopyridine (MP) reacts rapidly with nitrous acid in mildly acid aqueous solution (via the thione tautomer) to give an unstable 5-nitroso ion (SNO+) in a reversible process with an equilibrium constant (KN) of ca. 1 × 105 dm6 mol-2. SNO+ is readily detected by two peaks in the UV spectrum at 295 and 240 nm with extinction coefficients 9600 and 9300 dm3 mol-1 cm-1 respectively. MP is regenerated when the solution is made alkaline. Kinetic measurements made on the nitrosation reaction give a value of 8200 dm6 mol-2 s-1 for the third order rate constant k3 (defined by rate = k3 [MP] [HNO2] [H+]), which is close to that believed to be the diffusion-controlled limit for attack by NO+ (or H2NO2+). As expected there is marked catalysis by Cl- and Br-, and analysis of the kinetic results obtained from variation of measured rate constants with [halide ion] gave values of 3.5 × 109 and 3.7 × 109 dm3 mol-1 s-1 respectively for the bimolecular rate constants for NOCl and NOBr reactions with MP, again values close to the diffusion limit. The same experimental results also yielded values of 30 and 2400 dm3 mol-1 s-1 for the second order rate constants, for the reverse process of Cl- and Br- reaction with SNO+. Values for KN of 1.3 × 105 and 7.9 × 104 dm6 mol-2 were obtained from the halide catalysed reactions. In acid solution SNO+ decomposed to the disulfide (2,2′-dipyridyl disulflde) and NO (measured with a NO-electrode). Quenching of SNO+ at pH 7.4 gave UV spectroscopic evidence for the neutral deprotonated form (SNO) of SNO+ and there was a transformation to give mainly MP together with some disulfide. There was clear evidence that SNO+ (and maybe SNO) can act as an efficient nitrosating species: addition of the thiol N-acetylcysteine (at pH 6.15) resulted in the almost instantaneous decomposition of SNO. Addition of N-methylaniline (NMA) to an acidified solution of SNO+ resulted in quantitative N-methyl-N-nitrosoaniline formation and kinetic measurements of the nitrosation of NMA in the presence of MP showed marked catalysis at low [MP], which disappeared at higher [MP]. These results are quantitatively consistent with nitrosation via SNO+: catalysis disappears at higher [MP] when the nitrous acid is virtually completely converted to SNO+. A value of 1.7 × 105 dm3 mol-1 s-1 was obtained for the bimolecular rate constant for reaction of SNO+ with the free base form of NMA. MP is thus an excellent catalyst for electrophilic nitrosation. Under somewhat different conditions SNO+ can then act as a source of HNO2/NO2-, NO or NO+. The chemistry reported in this paper bears many similarities to that involved in the nitrosation of thioureas, and subsequent reactions of the S-nitrosothiouronium ions.
- Amado, Severino,Dicks, Andrew P.,Williams, D. Lyn H.
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p. 1869 - 1875
(2007/10/03)
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- Nucleophilic properties of thiourea towards aromatic halides
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Arylsulfides (and diaryldisulfides obtained spontaneously by oxidation of the arylsulfides during the work-up) and diarylsulfides can be obtained by substituting aryl radicals by the thiourea onion in liquid ammonia under an electrochemical inducement.
- Combellas,Dellerue,Mathey,Thiebault
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p. 539 - 542
(2007/10/03)
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- Thione-Disulfide Interchange of some Heterocyclic Tautomeric Thiones and their Symmetrical Bisulfides
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The UV/Vis spectroscopic properties of some symmetrical disulfides derived from potentially tautomeric thiones are investigated. Reversed thione-disulfide transformation is observed, and the influence of several factors including the nature of solvent, concentration, and UV irradiation, is studied. Possible implication of the tautomeric thiol form and the importance of this thione-disulfide redox system in biological aspects is suggested. A general scheme including monomer-dimer equilibrium, thione-thiol tautomeric equilibrium, and reversible thiol-disulfide redox behaviour is proposed in order to explain the factors affecting the overall thione-disulfide transformation.
- Stoyanov,Stoyanova,Antonov,Karagiannidis,Akrivos
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p. 495 - 504
(2007/10/03)
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- Spectroscopic and computational investigation of the ground and low excited states of some symmetrical heterocyclic disulfides
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The electronic absorption and emission spectra of some symmetrical heterocyclic disulfides are investigated. The reversible disulfide - thione transformation in water is discussed in view of the complex equilibrium processes present. UV irradiation and pH influence on the above transformation is also studied. The emission properties at room and low temperature are related to the computed molecular geometries of the ground and low excited states of the compounds.
- Stoyanov, Stefan,Stoyanova, Tatyana,Akrivos, Pericles D.,Karagiannidis, Petros,Nikolov, Peter
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p. 927 - 931
(2007/10/03)
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- Electrolytic Partial Fluorination of Organic Compounds. 13. Selective Anodic α-Fluorination of Nitrogen-Containing Heterocyclic Sulfides and Its Application to the Synthesis of Fluorinated Fused Heterocycles
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Highly regioselective anodic monofluorination of 2-pyridyl 6-pyrimidinyl sulfides was successfully carried out and fluorinated fused heterocycles were readily prepared in good yields using an anodically fluorinated sulfide.
- Erian, Ayman W.,Konno, Akinori,Fuchigami, Toshio
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p. 7245 - 7248
(2007/10/02)
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- Deoxydative Thiation of 3-Substituted Pyridine N-Oxides with 4-Methoxytoluene-α-thiol: A Divergent Route to Pyridinethiols
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Synthesis of 3-substituted 2-pyridinethiols was achieved by thiation of pyridine N-oxides with 4-methoxytoluene-α-thiol in the presence of diethylcarbamoyl chloride followed by cleavage of the resulting sulfides.The case of substitution was shown to be affected by nucleophilicity of the N-oxide oxygen.Addition of zinc bromide to the reaction, a need for triethylamine, decreased most of the yield for thiation products but the formation of 3-methoxy-2-methoxybenzylthiopyridine was only improved.A plausible mechanism of the substitution, particularly β-thiation to the N-oxide function, is discussed compared with the regiochemistry observed in the reaction with diethoxyphosphoryl chloride instead of diethylcarbamoyl chloride.The debenzylation to pyridinethiol was also found to be dependent on the electron-density in the pyridine ring.
- Sato, Nobuhiro,Nagano, Eiichi
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p. 691 - 698
(2007/10/02)
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- Intramolecular Addition of a Dioxolanyl Radical to the Indole Nucleus: Preparation of Enantiomerically Pure, Oxygenated Perhydro-3H-pyrroloindoles
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The cyclization of dioxolanyl radicals, which were generated by the Barton tartrate-derived thiohydroxamate ester (mixed anhydride) procedure, with an indole nucleus has been explored.The products derived from these reactions have been identified and their chemistry investigated with the goal of uncovering new entries into enantiomerically pure, mitomycin-like structures.Thus, the photolysis of 1-hydroxy-2-thiopyridone ester 8c and 1-hydroxy-4-methylthiazole-2(3H)-thione ester 8d has been conducted with UV and visible light.The photochemistry of the products, namely, dimer 9, dihydroindole 12a, indole 11, and thiazole 13c, derived from the thiohydroxamate esters and putative intermediates 18a and 18b, was also explored.
- Ziegler, Frederick E.,Harran, Patrick G.
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p. 2768 - 2773
(2007/10/02)
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- Toxin-targeted design for anticancer therapy. I: Synthesis and biological evaluation of new thioimidate heterobifunctional reagents
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In an effort to obtain a more potent and specific immunotoxin for cancer therapy, we designed a series of heterobifunctional linkers characterized by a thioimidate group linked to a S-acetyl thiol (4, 5) or substituted aryldithio group (6-10). These ligands were synthesized by a Pinner-type process from the corresponding nitrile derivatives obtained by thiol- disulphide exchange reaction, reaction with substituted benzene-sulphenyl chloride, or other known procedures. To check the reagent of choice for immunoconjugate preparation, we studied thioldisulphide exchange kinetics between the intermediate nitrile derivatives and cysteine. Among the tested aryldithio derivatives (6-10), we selected ethyl 3-(4-carboxamido- phenyldithio)propionthioimidate (CDPT, 9) for further studies. By analyzing the rate of incorporation of the linkers 4, 5, and 9 in a model immunoglobulin G protein, we found similar results with CDPT 9 and ethyl S- acetyl 3-mercaptopropionthioimidate ester hydrochloride (AMPT, 5) because both reagents showed a linear correlation between the number of introduced thiol groups and factors such as time and protein and reagent concentrations. Comparison of the two acetylthio-derivative ligands 4 and 5 showed that AMPT 5 was more stable toward deacetylation than ethyl S-acetyl 2- mercaptopropionthioimidate ester hydrochloride (AMAT, 4). By comparing the kinetic and biological parameters of seven new thioimidate linkers, we found that two of these (CDPT and AMPT) could be superior ligands for protein- protein conjugation. They offer advantages over the commercially available compounds, such as minimal perturbation of the protein structure, controlled reactivity, and good stability.
- Delprino,Giacomotti,Dosio,Brusa,Ceruti,Grosa,Cattel
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p. 506 - 512
(2007/10/02)
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