- Ionic reagent for controlling the gas-phase fragmentation reactions of cross-linked peptides
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Chemical cross-linking combined with proteolytic digestion and mass spectrometry (MS) is a promising approach to provide inter- and intramolecular distance constraints for the structural characterization of protein topologies and functional multiprotein complexes. Despite the relative straightforwardness of these methodologies, the identification and characterization of cross-linked proteins presents a significant analytical challenge, due to the complexity of the resultant peptide mixtures, as well as the array of inter-, intra-, or dead-end -cross-linked peptides that may be generated from a single cross-linking experiment. To address these issues, we describe here the synthesis, characterization, and initial evaluation of a novel fixed charge sulfonium ion-containing cross-linking reagent, S-methyl 5,5′-thiodipentanoylhydroxysuccinimide. The peptide products obtained by reaction with this reagent are all shown to fragment exclusively via facile cleavage of the C-S bond directiy adjacent to the fixed charge during CID-MS/MS, resulting in the formation of characteristic product ions that enable the presence and type (i.e., inter, intra, or dead-end) of the cross-linked products to be readily determined, independently of the proton mobility of the precursor ion. Subsequent isolation and dissociation of these products by MS3 provides additional structural information required for identification of the peptide sequences involved in the cross-linking reactions, as well as for characterization of the specific site(s) at which cross-linking has occurred. The specificity of these gas-phase fragmentation reactions, as well as the solubility and stability of the cross-linking reagent under aqueous conditions, suggests that this strategy holds great promise for use in future studies aimed at the structural analysis of large proteins or multiprotein assemblies.
- Lu, Yali,Tanasova, Marina,Borhan, Babak,Reid, Gavin E.
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- Thiophene backbone amide linkers, a new class of easily prepared and highly acid-labile linkers for solid-phase synthesis
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Solid-phase synthesis is of tremendous importance for small-molecule and biopolymer synthesis. Linkers (handles) that release amide-containing products after completion of solid-phase synthesis are widely used. Here we present a new class of highly acid-labile backbone amide linkers (BAL handles) based on 3,4-ethylenedioxythiophene (EDOT), which we have termed T-BAL. These thiophene linkers are synthesized in three convenient steps from commercially available EDOT. In the linker design, the spacer was introduced to the EDOT core either via a carbon-carbon bond or via a thioether linkage. Introduction of the spacer via a C-C bond was performed by a chemoselective Negishi coupling without transient protection of the aldehyde group to provide the T-BAL1 handle. Introduction via a thioether linkage was performed by a facile nucleophilic aromatic substitution between the brominated EDOT aldehyde and unprotected mercapto acids to provide T-BAL2 and T-BAL3 handles. The minimal use of protecting groups gave the corresponding linker molecules in few synthetic steps and in good yields. After anchoring of the linker to a polymeric support, introduction of the first amino acid was achieved by reductive amination, giving a secondary amine. A following acylation of the secondary amine with a symmetrical amino acid anhydride resulted in a backbone amide linkage between the handle and the growing substrate (e.g., peptide chain). After solid-phase synthesis, the substrates could be released from the resin by either low acid conditions using 1% TFA in CH2Cl2 or high acid conditions such as 50% TFA in CH2Cl2. Peptide thioesters could be released from the T-BAL1 handle under very mild conditions using aqueous acetic acid. Tert-butyl based protecting groups, tert-butyl esters, tert-butyl ethers, and Boc groups, as well as dimethyl acetals were relatively stable to these mild conditions for release of the peptides.
- Jessing, Mikkel,Brandt, Malene,Jensen, Knud J.,Christensen, Jorn B.,Boas, Ulrik
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- Amplified Self-Immolative Release of Small Molecules by Spatial Isolation of Reactive Groups on DNA-Minimal Architectures
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Triggering the release of small molecules in response to unique biomarkers is important for applications in drug delivery and biodetection. Due to low quantities of biomarker, amplifying release is necessary to gain appreciable responses. Nucleic acids have been used for both their biomarker-recognition properties and as stimuli, notably in amplified small-molecule release by nucleic-acid-templated catalysis (NATC). The multiple components and reversibility of NATC, however, make it difficult to apply in vivo. Herein, we report the use of the hybridization chain reaction (HCR) for the amplified, conditional release of small molecules from standalone nanodevices. We couple HCR with a DNA-templated reaction resulting in the amplified, immolative release of small molecules. We integrate the HCR components into single nanodevices as DNA tracks and spherical nucleic acids, spatially isolating reactive groups until triggering. This could be applied to biosensing, imaging, and drug delivery.
- Hennecker, Christopher,Mittermaier, Anthony,Prinzen, Alexander L.,Saliba, Daniel,Sleiman, Hanadi F.,Trinh, Tuan
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supporting information
p. 12900 - 12908
(2020/06/02)
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- Atmospheric Oxygen Mediated Radical Hydrothiolation of Alkenes
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A mild, metal-free, atmospheric oxygen-mediated radical hydrothiolation of alkenes (and alkyne) is reported. A variety of sulfur containing motifs including alkanethiols, thiophenols and thioacids undergo an atmospheric oxygen-mediated radical hydrothiolation reaction with a plethora of alkenes in good yield with excellent functional group compatibility, typically with short reaction times to furnish a range of functionalized products. Biomolecules proved tolerant to the conditions and the procedure is robust and easily executable requiring no specialized equipment. Concise mechanistic studies confirm the process proceeds through radical intermediates in a thiol-ene reaction manifold. The methodology offers an efficient “green” approach for thiol-ene mediated “click” ligation and a milder alternative to thermally initiated hydrothiolation processes.
- McCourt, Ruairí O.,Scanlan, Eoin M.
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supporting information
p. 15804 - 15810
(2020/10/26)
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- Modular Bidentate Hybrid NHC-Thioether Ligands for the Stabilization of Palladium Nanoparticles in Various Solvents
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The synthesis of four different bidentate hybrid NHC-thioether ligands is presented. The corresponding palladium nanoparticles are stable in various solvents, depending on the ligand used, and show high chemoselectivity in the hydrogenation of olefins. The solubility of the nanoparticles can be switched multiple times depending on the pH value of the solvent. XPS analysis (which shows a subtle shift in the binding energy) was identified as a convenient tool to establish the binding mode of NHC ligands.
- Rühling, Andreas,Schaepe, Kira,Rakers, Lena,Vonh?ren, Benjamin,Tegeder, Patricia,Ravoo, Bart Jan,Glorius, Frank
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supporting information
p. 5856 - 5860
(2016/05/09)
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- Access to Versatile β-Cyclodextrin Scaffolds through Guest-Mediated Monoacylation
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Herein, we report the selective mono-derivatization of heptakis[6-deoxy-6-(2-aminoethylsulfanyl)]-β-CD (1) through a guest-mediated covalent capture strategy. The use of guests functionalized with cleavable linkers enables the installation of an amine-orthogonal thiol group on the primary rim of 1 as a handle for further transformations to the β-CD scaffold. Applying this methodology, two novel monoderivatized β-CDs were obtained in good yield and high purity. Both of these monoacylated CDs were amenable to facile linker cleavage and further modification at the resulting thiol group. This methodology can be applied towards the synthesis heterofunctionalized β-CD constructs for analyte sensing, drug delivery, and other applications.
- Vurgun, Nesrin,G?mez-Biagi, Rodolfo F.,Nitz, Mark
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supporting information
p. 1062 - 1069
(2016/01/16)
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- 99mTc labeled myocardial imaging agents of long-chain fatty acid: An intermediate synthesis process research
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Myocardial fatty acid metabolic imaging agent can be used for studying the myocardial ischemia positioning, measurements reflect changes in myocardial metabolic function and the detection of myocardial cell survival, provide a reliable basis for the clinical diagnosis of cardiac disease. In this paper, we study the synthesis of fatty brominated products BSE, which is the intermediates of novel 99mTclabeled fatty acid metabolic imaging agent. The final yield of the product was 38 %, NMR spectroscopy confirmed very consistent the hydrogen peak displacement and integral spectrum area with the goal of formula. This synthetic route is convenient, simple, economic and has a potential value of industrial applications.
- Huo, Qing,Xue, Jingquan,Liu, Yu
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p. 8621 - 8624
(2013/11/06)
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- Structure dependence of long-chain [18F]fluorothia fatty acids as myocardial fatty acid oxidation probes
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In vivo imaging of regional fatty acid oxidation (FAO) rates would have considerable potential for evaluation of mammalian diseases. We have synthesized and evaluated 18F-labeled thia fatty acid analogues as metabolically trapped FAO probes to understand the effect of chain length, degree of unsaturation, and placement of the thia substituent on myocardial uptake and retention. 18-[18F]Fluoro-4-thia-(9Z)-octadec-9-enoic acid (3) showed excellent heart/background radioactivity concentration ratios along with highest retention in heart and liver. Pretreatment of rats with the CPT-1 inhibitor, POCA, caused >80% reduction in myocardial uptake of 16-[ 18F]fluoro-4-thiahexadecanoic acid (2) and 3, indicating high specificity for FAO. In contrast, 18-[18F]fluoro-4-thiaoctadecanoic acid (4) showed dramatically reduced myocardial uptake and blunted response to POCA. 18-[18F]Fluoro-6-thiaoctadecanoic acid (5) showed moderate myocardial uptake and no sensitivity of myocardial uptake to POCA. The results demonstrate relationships between structures of 18F-labeled thia fatty acid and uptake and their utility as FAO probes in various tissues.
- Pandey, Mukesh K.,Belanger, Anthony P.,Wang, Shuyan,Degrado, Timothy R.
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p. 10674 - 10684
(2013/02/23)
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- Synthesis and biological evaluation of thiol-based inhibitors of glutamate carboxypeptidase II: Discovery of an orally active GCP II inhibitor
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A series of 2-(thioalkyl)pentanedioic acids were synthesized and evaluated as inhibitors of glutamate carboxypeptidase II (GCP II, EC 3.4.17.21). The inhibitory potency of these thiol-based compounds against GCP II was found to be dependent on the number of methylene units between the thiol group and pentanedioic acid. A comparison of the SAR of the thiol-based inhibitors to that of the phosphonate-based inhibitors provides insight into the role of each of the two zinc-binding groups in GCP II inhibition. The most potent thiol-based inhibitor, 2-(3-mercaptopropyl)pentanedioic acid (IC50 = 90 nM), was found to be orally bioavailable in rats and exhibited efficacy in an animal model of neuropathic pain following oral administration.
- Majer, Pavel,Jackson, Paul F.,Delahanty, Greg,Grella, Brian S.,Ko, Yao-Sen,Li, Weixing,Liu, Qun,Maclin, Keith M.,Poláková, Jana,Shaffer, Kathryn A.,Stoermer, Doris,Vitharana, Dilrukshi,Yanjun Wang, Eric,Zakrzewski, Anthony,Rojas, Camilo,Slusher, Barbara S.,Wozniak, Krystyna M.,Burak, Eric,Limsakun, Tharin,Tsukamoto, Takashi
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p. 1989 - 1996
(2007/10/03)
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- Syntheses and first crystal structures of rhenium complexes derived from ω-functionalized fatty acids as model compounds of technetium tracers for myocardial metabolism imaging
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In an attempt to develop new technetium-based radiopharmaceuticals for the noninvasive diagnosis of myocardial metabolism, we have synthesized three examples of novel metal-containing fatty acid derivatives according to the "3+1 " mixed-ligand and the Schiff base/tricarbonyl design. The chelates contain the metal core in the oxidation states +5 and +1, respectively, and are attached to the end-position of a fatty acid chain. The complex formation was accomplished by ligand-exchange reactions with three different rhenium precursors, whereas the inactive rhenium metal was utilized as a surrogate of the technetium radionuclide. The molecular structures of the fatty acid complexes 7, 10 and 14 were determined by single-crystal X-ray diffraction analyses and impressively show a general problem in technetium tracer research, namely the significant structural alterations of bioactive molecules by coordination even to small metal chelates. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Jung, Christian M.,Kraus, Werner,Leibnitz, Peter,Pietzsch, Hans-Juergen,Kropp, Joachim,Spies, Hartmut
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p. 1219 - 1225
(2007/10/03)
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- Process for the preparation and purification of thiol-containing maytansinoids
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The present invention provides a process for the preparation and purification of thiol-containing maytansinoids comprising the steps of: (1) reductive hydrolysis of a maytansinoid C-3 ester with a reducing agent selected from the group consisting lithium trimethoxyaluminum hydride (LiAl(OMe)3H), lithium triethoxyaluminum hydride (LiAl(OEt)3H), lithium tripropoxyaluminum hydride (LiAl(OPr)3H), sodium trimethoxyaluminum hydride (NaAl(OMe)3H), sodium triethoxyaluminum hydride (NaAl(OEt)3H) and sodium tripropoxyaluminum hydride (NaAl(OPr)3H) to yield a maytansinol; (2) purifying the maytansinol to remove side products when present; (3) esterifying the purified maytansinol with a carboxylic acid to yield a mixture of an L- and a D-aminoacyl ester of maytansinol; (4) separating the L-aminoacyl ester of maytansinol from the reaction mixture in (3); (5) reducing the L-aminoacyl ester of maytansinol to yield a thiol-containing maytansinoid; and (6) purifying the thiol-containing maytansinoid.
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- S-4-Methoxytrityl mercapto acids: Synthesis and application
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4-Methoxytrityl (Mmt)-mercapto acids were obtained either by the reaction of mercapto acids with Mmt-chloride or by the reaction of halo acids with Mmt-thiol. The derivatives obtained were used in the solid-phase synthesis of small libraries of mercaptoacylamino acids and mercaptoacyl peptides. The removal of the Mmt-group was performed by treatment with trifluoroacetic acid (TFA) in dichloromethane (DCM) using triethylsilane (TES) as scavenger.
- Mourtas, Spyros,Gatos, Dimitrios,Kalaitzi, Vagiani,Katakalou, Christina,Barlos, Kleomenis
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p. 6965 - 6967
(2007/10/03)
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- Cytotoxic agents comprising maytansinoids and their therapeutic use
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A cytotoxic agent comprising one or more maytansinoids linked to a cell binding agent. A therapeutic agent for killing selected cell populations comprising: (a) a cytotoxic amount of one or more maytansinoids linked to a cell binding agent, and (b) a pharmaceutically acceptable carrier diluent or excipient. A method for killing selected cell populations comprising contacting a cell population or tissue suspected of containing cells from said selected cell population with a cytotoxic amount of a cytotoxic agent comprising one or more maytansinoids linked to a cell binding agent. An N-methyl-alanine-containing ester of maytansinol or an analogue of maytansinol, said N-methyl-alanine-containing ester comprising a linking group capable of linking an N-methyl-alanine-containing maytansinoid ester to a chemical moiety. N-methyl-cysteine-containing ester of maytansinol or an analogue of maytansinol.
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- Amine containing ester prodrugs of corticosteroids
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Novel solution stable ester prodrugs of corticosteroids of the formula STR1
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- Azole derivatives
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Azole derivatives of the formula SPC1 Wherein R1 is free or esterified carboxyl or other functionally modified carboxyl group, R2 and R3 each are aryl; A is Cn H2n in which n is an integer from 1 to 10, inclusive; and Z is O or S; and the physiologically acceptable salts thereof, possess, with good compatibility, excellent antiphlogistic activity and, in particular, influence favorably the chronic progressive diseases of the joints, e.g., arthritis. They can be prepared from compounds of the formula SPC2 Wherein X1 is a group convertible into the group --S--A--R1, and R2 and R3 have the values given above.
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