- Synthesis and delivery of a stable phosphorylated ubiquitin probe to study ubiquitin conjugation in mitophagy
-
Protein post-translational modifications are involved in essentially all aspects of cellular signaling. Their dynamic nature and the difficulties in installing them using enzymatic approaches limits their direct study in human cells. Reported herein is the first synthesis, delivery and cellular study of a stable phosphoubiquitin probe. Our results compare Parkin's substrate preference during mitophagyviadirect visualization of a phosphorylated ubiquitin probe in the cellular environment.
- Mann, Guy,Satish, Gandhesiri,Sulkshane, Prasad,Mandal, Shaswati,Glickman, Michael H.,Brik, Ashraf
-
supporting information
p. 9438 - 9441
(2021/09/22)
-
- Rhodium(I) and Iridium(I) N-Heterocyclic carbene complexes of imidazolium functionalized amino acids and peptides
-
The conjugation of organometallic complexes to peptides is generally achieved through covalent organic linkages of the metal's ligand to the peptide. Examples of direct coordination to metal centers by amino acid side chain residues remain rare. In one such example, side chain methylation of the natural amino acid histidine (His) resulted in an imidazolium functionalized amino acid which was used for the synthesis of rhodium(I), iridium(I), iridium(III), palladium(II) and ruthenium(III) N-heterocyclic carbene (NHC) complexes of the single amino acid and peptides containing this amino acid. Here, we have synthesized two new, non-natural imidazolium functionalized amino acid derivatives, which were used for solid phase peptide synthesis and for the synthesis of [M(COD)(NHC)Cl] (COD = 1,5 cyclooctadiene) complexes of Rh(I) and Ir(I). In total, six new complexes of the single amino acids and four complexes where the amino acids are present in a peptide environment were synthesized. Their characterization provides convincing evidence of conversion of the imidazolium moiety to an NHC ligand and thus the presence of a direct metal-carbon bond between the metal center and the amino acid side chain. Therefore, our compounds represent unique examples of peptide-conjugated complexes that bear the potential to be used for the synthesis of N-heterocyclic carbene complexes conjugated to cancer cell targeting peptides.
- Daubit, Isabelle Marie,Wolf, Jonas,Metzler-Nolte, Nils
-
supporting information
(2020/01/13)
-
- Design, synthesis, and evaluation of compounds capable of reducing Pseudomonas aeruginosa virulence
-
Anti-virulence approaches in the treatment of Pseudomonas aeruginosa (PA)-induced infections have shown clinical potential in multiple in vitro and in vivo studies. However, development of these compounds is limited by several factors, including the lack of molecules capable of penetrating the membrane of gram-negative organisms. Here, we report the identification of novel structurally diverse compounds that inhibit PqsR and LasR-based signaling and diminish virulence factor production and biofilm growth in two clinically relevant strains of P. aeruginosa. It is the first report where potential anti-virulent agents were evaluated for inhibition of several virulence factors of PA. Finally, co-treatment with these inhibitors significantly reduced the production of virulence factors induced by the presence of sub-inhibitory levels of ciprofloxacin. Further, we have analyzed the drug-likeness profile of designed compounds using quantitative estimates of drug-likeness (QED) and confirmed their potential as hit molecules for further development.
- Hossain, Mohammad Anwar,Sattenapally, Narsimha,Parikh, Hardik I.,Li, Wei,Rumbaugh, Kendra P.,German, Nadezhda A.
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supporting information
(2019/11/26)
-
- Method for synthesizing L L-(+)-selenomethionine (by machine translation)
-
The synthetic route disclosed L - (+) - by the invention has, L - (+) - the advantages that the raw materials, are easy to obtain, the reaction conditions are, mild, the reaction conditions are mild, the separation, and purification are easy, L - (+) - and the; method L - (+) - is easy, to separate and purify L - (+) - L - (+) - L - (+) . (by machine translation)
- -
-
Paragraph 0041-0044; 0055; 0064; 0073; 0082
(2019/12/25)
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- Discovery of new A- and B-type laxaphycins with synergistic anticancer activity
-
Two new cyclic lipopeptides termed laxaphycins B4 (1) and A2 (2) were discovered from a collection of the marine cyanobacterium Hormothamnion enteromorphoides, along with the known compound laxaphycin A. The planar structures were solved based on a combined interpretation of 1D and 2D NMR data and mass spectral data. The absolute configurations of the subunits were determined by chiral LC-MS analysis of the hydrolysates, advanced Marfey's analysis and 1D and 2D ROESY experiments. Consistent with similar findings on other laxaphycin A- and B-type peptides, laxaphycin B4 (1) showed antiproliferative effects against human colon cancer HCT116 cells with IC50 of 1.7 μM, while laxaphycins A and A2 (2) exhibited weak activities. The two major compounds isolated from the sample, laxaphycins A and B4, were shown to act synergistically to inhibit the growth of HCT116 colorectal cancer cells.
- Cai, Weijing,Matthew, Susan,Chen, Qi-Yin,Paul, Valerie J.,Luesch, Hendrik
-
p. 2310 - 2319
(2018/04/02)
-
- Combining Aldolases and Transaminases for the Synthesis of 2-Amino-4-hydroxybutanoic Acid
-
Amino acids are of paramount importance as chiral building blocks of life, for drug development in modern medicinal chemistry, and for the manufacture of industrial products. In this work, the stereoselective synthesis of (S)- and (R)-2-amino-4-hydroxybutanoic acid was accomplished using a systems biocatalysis approach comprising a biocatalytic one-pot cyclic cascade by coupling of an aldol reaction with an ensuing stereoselective transamination. A class II pyruvate aldolase from E. coli, expressed as a soluble fusion protein, in tandem with either an S- or R-selective, pyridoxal phosphate dependent transaminase was used as a catalyst to realize the conversion, with formaldehyde and alanine being the sole starting materials. Interestingly, the class II pyruvate aldolase was found to tolerate formaldehyde concentrations of up to 1.4 M. The cascade system was found to reach product concentrations for (S)- or (R)-2-amino-4-hydroxybutanoic acid of at least 0.4 M, rendering yields between 86% and >95%, respectively, productivities of >80 g L-1 d-1, and ee values of >99%.
- Hernandez, Karel,Bujons, Jordi,Joglar, Jesús,Charnock, Simon J.,Domínguez De María, Pablo,Fessner, Wolf Dieter,Clapés, Pere
-
p. 1707 - 1711
(2017/08/15)
-
- Reaction of (S)-homoserine lactone with Grignard reagents: synthesis of amino-keto-alcohols and β-amino acid derivatives
-
The ring-opening reaction of homoserine lactone with phenylmagnesium bromides was systematically examined. A reliable method to achieve β-amino acid precursors was developed by tuning the reaction conditions to favor mono-addition to the carbonyl moiety of the lactone.
- Gündo?du, ?zlem,Turhan, P?nar,K?se, Aytekin,Altunda?, Ramazan,Kara, Yunus
-
p. 1163 - 1168
(2017/09/15)
-
- Synthesis of Chiral Bicyclic Guanidinium Salts using Di(imidazole-1-yl)methanimine
-
A detailed account of the synthesis of chiral bicyclic guanidinium salts is presented. This work represents the first systematic investigation of an approach toward the challenging target molecules via a key guanylation step employing di(imidazole-1-yl)methanimine (6) followed by a two-fold cyclization, which resulted in guanidinium salts 8 and 10. Factors governing the regioselectivity of the final cyclization step are discussed based on further data obtained in the course of the attempted syntheses of two additional bicyclic guanidinium salts.
- Turo?kin, Aleksej,Honeker, Roman,Raven, William,Selig, Philipp
-
p. 4516 - 4529
(2016/07/06)
-
- Large-scale, protection-free synthesis of Se-adenosyl-l-selenomethionine analogues and their application as cofactor surrogates of methyltransferases
-
S-Adenosyl-l-methionine (SAM) analogues have previously demonstrated their utility as chemical reporters of methyltransferases. Here we describe the facile, large-scale synthesis of Se-alkyl Se-adenosyl-l-selenomethionine (SeAM) analogues and their precursor, Se-adenosyl-l-selenohomocysteine (SeAH). Comparison of SeAM analogues with their equivalent SAM analogues suggests that sulfonium-to-selenonium substitution can enhance their compatibility with certain protein methyltransferases, favoring otherwise less reactive SAM analogues. Ready access to SeAH therefore enables further application of SeAM analogues as chemical reporters of diverse methyltransferases.
- Bothwell, Ian R.,Luo, Minkui
-
supporting information
p. 3056 - 3059
(2014/06/23)
-
- Deracemization of amino acids by coupling transaminases of opposite stereoselectivity
-
Biocatalytic deracemization of amino acids without relying on oxidase-based deamination of an unwanted enantiomer was demonstrated by coupling a-and w-transaminases displaying opposite stereoselectivity. This strategy employs isopropylamine and a keto acid as cosubstrates and is free of generation of hydrogen peroxide which is troublesome in the conventional oxidase-based methods.
- Park, Eul-Soo,Shin, Jong-Shik
-
p. 3505 - 3509
(2015/02/19)
-
- Enantiopure azetidine-2-carboxamides as organocatalysts for direct asymmetric aldol reactions in aqueous and organic media
-
A family of enantiopure azetidine-2-caboxamides was asymmetrically synthesized, and was examined as organocatalyst in direct aldol reactions. A well chosen chiral azetidine-2-caboxamide was found to smoothly catalyze the direct aldol reaction of various benzaldehydes with acetone in brine, and β-hydroxy ketones were produced with enantiomeric excess up to 96%. The reaction of benzaldehydes with cyclic ketones also led to the formation of anti-products in diastereomeric ratio up to 99:1 and enantiomeric excess up to 99%.
- Song, Xixi,Liu, Ai-Xiang,Liu, Shan-Shan,Gao, Wen-Chao,Wang, Min-Can,Chang, Junbiao
-
p. 1464 - 1470
(2014/02/14)
-
- Synthesis and biological evaluation of novel curcuminoid derivatives
-
Curcuminoids have been reported to possess multiple bioactivities, such as antioxidant, anticancer and anti-inflammatory properties. Three novel series of curcuminoid derivatives (11a-h, 15a-h and 19a-d) with enhanced bioactivity have been synthesized. Among the synthesized compounds, 11b exhibited the most significant activity with an MIC of 0.5 μ M /mL against selected medically important Gram-positive cocci (S aureus and S viridans) and Gram-negative bacilli (E. coli and E. cloacae). The derivatives exhibited remarkable results in an antioxidant test with an IC50 2.4- to 9.3-folder smaller than curcuminoids. With respect to antiproliferative activity against Hep-G2, LX-2, SMMC7221 and MDA-MB-231, the derivatives exhibited an effect stronger than curcuminoids with an IC50 ranging from 0.18 to 4.25 μ M.
- Cao, Ya-Kun,Li, Hui-Jing,Song, Zhi-Fang,Li, Yang,Huai, Qi-Yong
-
p. 16349 - 16372
(2015/01/08)
-
- INTERMEDIATES OF SITAGLIPTIN AND PREPARATION PROCESS THEREOF
-
Disclosed are intermediates of Sitagliptin, a preparation process thereof, and a process for synthesizing Sitagliptin using these intermediates. Sitagliptin is synthesized by using chiral amino compounds as a raw material, without having to build a chiral center with a chiral asymmetric catalytic hydrogenation, and high-pressure hydrogenation is avoided.
- -
-
Paragraph 0048; 0049
(2013/10/22)
-
- INTERMEDIATES OF SITAGLIPTIN AND PREPARATION PROCESS THEREOF
-
Disclosed are intermediates of Sitagliptin, a preparation process thereof, and a process for synthesizing Sitagliptin using these intermediates. Sitagliptin is synthesized by using chiral amino compounds as a raw material, without having to build a chiral center with a chiral asymmetric catalytic hydrogenation, and high-pressure hydrogenation is avoided.
- -
-
Paragraph 0094-0095
(2013/11/05)
-
- Concise Synthesis of Enantiomerically Pure (1′S,2′R)-and (1′R,2′S)-2S-Amino-3-(2′-aminomethyl-cyclopropyl)propionic Acid: Two E-Diastereoisomers of 4,5-Methano-l-lysine
-
A concise synthesis of both E-isomers of 2S-amino-3-(2′-aminomethyl- cyclopropyl)propionic acid, new methano-l-lysines, is described. The synthetic route includes nine steps from l-methionine, with a key step involving the cyclopropanation of an intermediate E-allylic alcohol. The resultant hydroxymethylcyclopropanes were readily separated and converted into the title α-amino acids. The stereochemistry around the cyclopropane rings was deduced by conducting the cyclopropanation in the presence of N,N,N′,N′-tetramethyl-d-tartaric acid diamide butylboronate, a chiral controller which is known to favour the production of S-hydroxymethyl cyclopropanes from allylic alcohols.
- Altamore, Timothy M.,Nguyen, Oanh T. K.,Churches, Quentin I.,Cavanagh, Kate,Nguyen, Xuan T. T.,Duggan, Sandhya A. M.,Krippner, Guy Y.,Duggan, Peter J.
-
p. 1105 - 1111
(2013/09/24)
-
- N -acyl-homoserine lactones from enterobacter sakazakii (Cronobacter spp.) and their degradation by bacillus cereus enzymes
-
A chemical study of acyl-homoserine lactones (acyl-HSLs) produced by Enterobacter sakazakii resulted in the identification of three molecules: (S)-N-heptanoyl-HSL, (S)-N-dodecanoyl-HSL and (S)-N-tetradecanoyl-HSL. Mixed cultures of E. sakazakii and Bacillus cereus depleted E. sakazakii acyl-HSLs, suggesting acyl-HSL degradation by B. cereus hydrolases (hydrolysis of the lactone or amide moiety). The expression of B. cereus acyl-HSL lactonase and acyl-homoserine acylase was confirmed by monitoring the biotransformation of (S)-N-dodecanoyl-HSL into (S)-N-dodecanoyl-homoserine, dodecanoic acid and homoserine in the presence of B. cereus whole cells, using electrospray-mass spectrometry (ESI-MS).
- Da Silva Araujo, Francisca Diana,Esper, Luciana Maria Ramires,Kuaye, Arnaldo Yoshiteru,Sircili, Marcelo Palma,Marsaioli, Anita Jocelyne
-
scheme or table
p. 585 - 592
(2012/04/18)
-
- Enantioselective synthesis of (2S,3′R,7′Z)-N -(3′-hydroxy-7′-tetradecenoyl)-homoserine lactone
-
A concise enantioselective total synthesis of (2S,3′R,7′Z)-N- (3′-hydroxy-7′-tetradecenoyl)-homoserine lactone is described. Key feature of this protocol is a catalytic asymmetric hydrogenation and a prophenol-zinc-catalyzed diazo addition to imine reaction as genesis of chirality. Moreover, flexibility is built in the synthesis to generate enantioenriched analogs using catalytic amount of enantioenriched C 2-symmetric ligands.
- Kumaraswamy, Gullapalli,Jayaprakash, Neerasa
-
supporting information; experimental part
p. 6500 - 6502
(2011/02/22)
-
- Mycenaaurin A, an antibacterial polyene pigment from the fruiting bodies of mycena aurantiomarginata
-
A new polyene pigment, mycenaaurin A (1), was isolated from fruiting bodies of Mycena aurantiomarginata. Mycenaaurin A consists of a tridecaketide that is flanked by two amino acid moieties. These are likely to be derived biosynthetically from S-adenosylmethionine. The tridecaketide itself contains an α-pyrone, a conjugated hexaene, and an isolated alkenyl moiety. The structure of the new pigment was established by 2D NMR spectroscopic methods and APCIMS. The absolute configuration of the four stereogenic centers was determined by degradation of 1 by ozonolysis and GC-MS comparison of the resulting fragments, after appropriate derivatization, with authentic synthetic samples. Mycenaaurin A (1) might act as a constitutive defense compound, since it exhibits antibacterial activity against the Gram-positive bacterium Bacillus pumilus.
- Jaeger, Robert J. R.,Spiteller, Peter
-
experimental part
p. 1350 - 1354
(2010/10/21)
-
- PROCESSES FOR PREPARING AMINO-SUBSTITUTED GAMMA-LACTAMS
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The present application describes general process for the preparation of amino-substitued gamma-lactams involving the reaction of synthons of the general Formulae (I) and (VI): with amines. The processes are amenable to solid phase synthetic techniques and therefore allow the efficient incorporation of amino-substitued gamma-lactams into a wide variety of structural scaffolds, including, in particular peptides.
- -
-
Page/Page column 27
(2010/10/03)
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- Evaluation of enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl) methanol for catalytic asymmetric addition of organozinc reagents to aldehydes
-
(Chemical Equation Presented) A facile and practical approach to preparation of enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)-methanol was developed from cheap and easily available L-(+)-methionine. Synthetic highlights include the three-step, one-pot construction of the chiral azetidine ring and the development of an improved one-step procedure for the synthesis of the key intermediate L-2-amino-4-bromobutanoic acid. Enantiopure N-(ferrocenylmethyl)azetidin-2-yl(diphenyl)methanol was evaluated for catalytic asymmetric addition of organozinc reagents to aldehydes. The asymmetric ethylation, methylation, arylation, and alkynylation of aldehydes achieved enantioselectivity of up to 98.4%, 94.1%, 99.0%, and 84,6% ee, respectively, in the presence of a catalytic amount of chiral N-(ferrocenylmethyl)azetidin-2- yl(diphenyl)methanol. Our results demonstrated further that the four-membered heterocycle-based backbone was a good potential chiral unit for the catalytic asymmetric induction reaction, and the hindrance of the bulky ferrocenyl group, compared to a phenyl group, played an important role in the enantioselectivities. A possible transition for the catalytic asymmetric addition has been proposed on the basis of the crystal structure of the chiral ligand 3b including two HOAc molecules and previous studies.
- Wang, Min-Can,Zhang, Qing-Jian,Zhao, Wen-Xian,Wang, Xiao-Dan,Ding, Xue,Jing, Tao-Tao,Song, Mao-Ping
-
p. 168 - 176
(2008/09/17)
-
- Syntheses of the P-methylase substrates of the bialaphos biosynthetic pathway
-
(Chemical Equation Presented) Genetic studies suggest that either N-acetyldemethyl phosphinothricin (1, N-AcDMPT) or N-acetyldemethyl phosphinothricin tripeptide (2, N-AcDMPTT) is the substrate for the P-methylation reaction in the biosynthesis of phosphinothricin tripeptide (PTT), which is widely used as an herbicide. To study the mechanism for this unique P-methylation reaction catalyzed by the BcpD protein and the functions of the unusual nonribosomal peptide synthetases involved in PTT biosynthesis, this work reports the chemical syntheses of 1 and 2.
- Xiao, Youli,Lee, Kent,Liu, Pinghua
-
supporting information; experimental part
p. 5521 - 5524
(2009/06/28)
-
- Stable organophosphorus analogues of S-adenosylmethionine and S-methylmethionine
-
The organophosphorus analogues of the biologically significant sulfonium compounds S-adenosylmethionine and S-methylmethionine are much more stable than their carboxylic prototypes.
- Alferov, Kirill V.,Zhukov, Yurii N.,Khurs, Elena N.,Khomutov, Radii M.
-
p. 243 - 244
(2007/10/03)
-
- Under-flame Reaction of Sulfur-containing Amino Acids by a Hydrogen-Oxygen Flame
-
Methionine was subjected to a flame-induced reaction in water or in an aqueous formic acid solution by using a hydrogen (50%)-oxygen (50%), hydrogen (87%)-oxygen (13%) and hydrogen diffusion flame. Besides the already-known stepwise oxidation by a hydroxyl radical, the contribution of a hydrogen atom from the flame to the reaction was recognized when the hydrogen-rich mixtures were employed. Homoserine was obtained under all the reaction conditions employed here, and glutamic acid when employing aqueous formic acid as a solvent. A common intermediate, the 3-carboxy-3-aminopropyl radical, appeared to exist in the reaction pathway. A coupling reaction of this radical with a hydrogen atom, hydroxyl radical and hydroxycarbonyl radical afforded 2-aminobutyric acid, homoserine and glutamic acid, respectively. Lanthionine and S-methylcysteine underwent the same reactions. Increasing the hydrogen content of the fuel and adding formic acid to the solvent resulted in retarding the reaction rate. The latter modification of the reaction system also brought about greater stability of the reaction products.
- Nomoto, Shinya,Shimoyama, Akira,Shiraishi, Susumu,Seno, Tomoyuki,Sahara, Denzo
-
p. 643 - 649
(2007/10/03)
-
- Flame-induced reactions of sulfur-containing amino acids in an aqueous solution
-
Hydrogen-oxygen flames, when blown against an aqueous solution of methionine, induced conversion reactions to homoserine, 2-aminobutyric acid and glutamic acid. Besides the already-known reactions by a hydroxyl radical, a contribution of a hydrogen atom from hydrogen-rich flames to the reaction was recognized. We successfully controlled the vigorous oxidation of the system using a radical scavenger.
- Nomoto, Shinya,Shimoyama, Akira,Shiraishi, Susumu
-
p. 1009 - 1012
(2007/10/03)
-
- Cosmetic composition
-
A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
- -
-
-
- Synthesis of (2S)-O-phosphohomoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers: Probes for the pyridoxal phosphate-dependent threonine synthase reaction
-
A short efficient synthesis of the threonine synthase substrate (2S)-O-phosphohomoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers is described. The synthetic route also provides access to (2S)-homoserine and its C-2 deuteriated and C-3 chirally deuteriated isotopomers in high yield. Preliminary deuterium isotope effect determinations performed using the deuteriated (2S)-O-phosphohomoserines and threonine synthase from E. coli indicate that the removal of protons from both C-2 and C-3 is kinetically important.
- Barclay, Fiona,Chrystal, Ewan,Gani, David
-
p. 683 - 689
(2007/10/03)
-
- Optical resolution by preferential crystallization of (RS)-α-amino-γ-butyrolactone hydrochloride
-
(RS)-α-Amino-γ-butyrolactone hydrochloride [(RS)-ABL·HCl] was found to exist as a conglomerate based on the infrared spectrum, solubility, and melting point. Optical resolution by preferential crystallization of (RS)-ABL·HCl was achieved to yield (R)- and (S)-ABL·HCl. The obtained (R)- and (S)-ABL·HCl were recrystallized, taking into account the solubility of (RS)-ABL·HCl to give optically pure (R)- and (S)-ABL·HCl.
- Shiraiwa, Tadashi,Miyazaki, Hideya,Ohta, Atsushi,Waki, Yukitaka,Yasuda, Masahiro,Morishita, Toshimitsu,Kurokawa, Hidemoto
-
p. 2322 - 2325
(2007/10/03)
-
- Synthesis of (S)-2-amino-1,1-diphenylbutan-4-ol; conversion of an α-amino acid into an α-(diphenylmethyl) amine without loss of optical purity
-
The title amino-alcohol 4 is an intermediate for the preparation of chiral bicyclic amidines and guanidines, and also for polyamines with potential as ligands in enantioselective catalysis. It has been synthesized from (S)-methionine 1 via (S)-homoserine lactone 2 and amino-diol 3. Hydrogenolysis of the doubly benzylic hydroxyl group in 3 proved non-trivial, but was eventually achieved through the application of catalytic transfer methodology to the bis-acetyl derivative 14.
- Boyle,Davis,Dempsey,Hosken
-
p. 2819 - 2828
(2007/10/03)
-
- Selective Inhibition of Benzyl Ether Hydrogenolysis with Pd/C Due to the Presence of Ammonia, Pyridine or Ammonium Acetate
-
Ammonia, pyridine and ammonium acetate were found to be extremely effective as inhibitors of Pd/C catalyzed benzyl ether hydrogenolysis.While olefin, Cbz, benzyl ester and azide functionalities were hydrogenated smoothly, benzyl ethers were not cleaved in the presence of these additives.
- Sajiki, Hironao
-
p. 3465 - 3468
(2007/10/02)
-
- Synthesis of L-O-Phosphohomoserine and its C-3 Chirally Deuteriated Isotopomers: Probes for the Pyridoxal Phosphate Dependent Threonine Synthase Reaction
-
A short efficient synthesis of the threonine synthase substrate L-O-phosphohomoserine and its C-3 chirally deuteriated isotopomers is described; the route also provides access to L-homoserine and its C-3 chirally deuteriated isotopomers in high yield.
- Barclay, Fiona,Chrystal, Ewan,Gani, David
-
p. 815 - 816
(2007/10/02)
-
- Synthesis of L-(+)-selenomethionine
-
A novel three-pot synthesis of L-(+)-selenomethionine suitable for small and large scale preparations is presented. The method gives high optical purity and avoids evil smelling selenium species.
- Koch,Buchardt
-
p. 1065 - 1067
(2007/10/02)
-
- Synthesis of Nonproteinogenic (R)- or (S)-Amino Acids. - Analogues of Phenylalanine, Isotopically Labelled and Cyclic Amino Acids from tert-Butyl 2-(tert-Butyl)-3-methyl-4-oxo-1-imidazolidinecarboxylate (Boc-BMI)
-
The enantiomerically pure glycine derivatives (R)- and (S)-Boc-BMI, commercially available on a kg scale, are used as starting materials (Scheme 1) for the preparation of (i) open-chain amino acids such as α-deuterio amino acids (4,5), β-arylalanines (2), aspartic acid derivatives (6, 7a, 8), or ω-halo amino acids (7b,c, 12, 13, 16, 17, 19, 22), (ii) of α-aminocycloalkanecarboxylic acids (9, 11), and (iii) of heterocyclic α-amino acids (14, 15, 18, 20) containing azetidine, pyrrolidine, piperidine or perhydroazepine rings.Inversion by deprotonation/protonation ordeuteration allows to prepare either enantiomer of an amino acid from the same Boc-BMI enantiomer (Scheme 5).Effects of additives such as the cyclic urea DMPU, lithium salts, or secondeary amines upon the reactivity of lithium enolates are discussed and, in part, exploited.
- Seebach, Dieter,Dziadulewicz, Edward,Behrendt, Linda,Cantoreggi, Sergio,Fitzi, Robert
-
p. 1215 - 1232
(2007/10/02)
-
- A METHOD FOR REDUCTIVE CLEAVAGE OF N-GLYCOSYLAMIDE CARBOHYDRATE-PEPTIDE BOND
-
A new, mild method for the splitting of N-linked oligosaccharides from glycoproteins includes treatment of glycoproteins (ovomucoid, flavoprotein, ribonuclease B, hemagglutinin, or transferrin) with 2 M LiBH4 in 25 mM LiOH - 50 mM Li citrate - 70percent aqueous tert-butyl alcohol (5 h, 45 deg C), followed by hydrolysis of the resulting glycosylamine with aqueous acetic acid.The oligosaccharides formed were easily isolated by gel filtration and cation-exchange chromatography in 60-80 percent yields.The reaction was accompanied by the intense reductive cleavage of peptide bonds with formation of amino alcohols, but N-deacetylation of hexosamine was completely excluded.The optimal conditions of this reaction were chosen by use of a model glycopeptide, 2-acetamido-4-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-1-N-(4-L-aspartoyl)-2-deoxy-β-D-glucopyranosylamine
- Likhosherstov, Leonid M.,Novikova, Olga S.,Piskarev, Vladimir E.,Trusikhina, Elena E.,Derevitskaya, Varvara A.,Kochetkov, Nikolay K.
-
p. 155 - 164
(2007/10/02)
-
- USE OF L-ASPARTIC ACID β-SEMIALDEHYDE IN THE SYNTHESIS OF MORE COMPLEX NON PROTEIN AMINO ACIDS
-
The potential of aspartic acid β-semialdehyde as a starting material for the synthesis of more complex amino acids is illustrated by its conversion to L-2-amino hept 4,6-dienoic acid and 2S,4R,5S-2-amino-4,5,6 trihydroxy hexanoic acid.
- Baldwin, J. E.,Flinn, A.
-
p. 3605 - 3608
(2007/10/02)
-
- PTAQUILOSIDE, A POTENT CARCINOGEN ISOLATED FROM BRACKEN FERN PTERIDIUM AQUILINUM VAR. LATIUSCULUM: STRUCTURE ELUCIDATION BASED ON CHEMICAL AND SPECTRAL EVIDENCE, AND REACTIONS WITH AMINO ACIDS, NUCLEOSIDES, AND NUCLEOTIDES
-
The structure of ptaquiloside (I), a potent carcinogenic compound isolated from bracken fern, Pteridium aquilinum var. latiusculum has been elucidated on the basis of chemical and spectral evidence.The dienone 3 generated from 1 under alkaline conditions was shown to be a strong alkylating agent.For the purpose of obtaining the preliminary information on chemical modification of biopolymers such as proteins and DNA with the dienone 3, reactions of 3 with amino acids, nucleosides, and nucleotides have been carried out and the alkylated products have been characterized.
- Ojika, Makoto,Wakamatsu, Kazumasa,Niwa, Haruki,Yamada, Kiyoyuki
-
p. 5261 - 5274
(2007/10/02)
-
- General Method of Diastereo- and Enantioselective Synthesis of β-Hydroxy-α-amino Acids by Condensation of Aldehydes and Ketones with Glycine
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The condensation of formaldehyde with a Ni(II) complex of glicyne Schiff base with (S)-2-acetophenone (1) or (S)-2-benzophenone (2) in CH3OH at 25 deg C in the presence of Et3N yields (S)-Ser with an enantiomeric excess (ee) of 80-90percent.The same reaction gives rise to (R)-Ser with an ee greater than 80percent in the presence of more than 0.2 N CH3ONa, α-(hydroxymethyl) serine being formed in negligible quantities.The reaction of benzaldehyde, 3,4-(methilenedioxy)benzaldehyde, and acetaldehyde with these Gly complexes in 0.2 N CH3ONa at 25 deg C yields β-hydroxy-α-amino acids: (R)-β-phenylserine, (R)-3,4-(methylenedioxy)-β-phenylserine, and (R)-threonine, respectively, with a threo/allo ratio ranging from 10:1 up to over 50:1 and ee more than 80percent.Condensation with acetone yields (R)-β-hydroxyvaline with an enantiomeric purity of 70percent.The enantiomerically pure β-hydroxy-α-amino acids can be obtained from pure diastereomers, isolated by chromatography on silica or Toyopearl HW-60.The initial reagents 1 and 2 were recovered with 60-98percent yield.The stereochemical mechanism of the reaction is discussed.
- Belokon, Yuri N.,Bulychev, Alexander G.,Vitt, Sergei V.,Struchkov, Yuri T.,Batsanov, Andrei S.,et al.
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p. 4252 - 4259
(2007/10/02)
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- THE STRUCTURE OF PYOVERDINE pa, THE SIDEROPHORE OF PSEUDOMONAS AERUGINOSA
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The structure of Pyoverdine Pa, the siderophore of Pseudomonas aeruginosa, was elucidated by degradation, by FAB mass spectrometry and by NMR, it consists of linear octapeptide bound to a 2,3-diamino-6,7-dihydroxyquinoline derived chromophore.
- Wendenbaum, S.,Demange, P.,Dell, A.,Meyer, J. M.,Abdallah, M. A.
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p. 4877 - 4880
(2007/10/02)
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- Synthesis and rearrangements of D-glucosyl esters of aspartic acid linked through the 1- or 4-carboxyl group.
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Catalytic hydrogenation of 2,3,4,6-tetra-O-benzyl-1-O-[1-benzyl N-(benzyloxycarbonyl)-L-aspart-4-oyl]-alpha-D-glucopyranose (1alpha) in acetic acid-2-methoxyethanol gave 1-O-(L-beta-aspartyl)alpha-D-glucopyranose (2alpha) contaminated with 2-O-(L-alpha-aspartyl)-D-glucopyranose (8). Evidence that 8 was formed from the 1-oyl isomer of 1alpha, namely 2,3,4,6-tetra-O-benzyl-1-O-[4-benzyl N-(benzyloxycarbonyl)-L-aspart-1-oyl]-alpha-D-glucopyranose (7alpha), via 1 leads to 2 acyl migration, was obtained by submitting the deprotected D-glucosyl ester to successive N-acetylation, esterification, and O-acetylation; the final product was identified as a approximately 4:1 mixture of 2,3,4,6-tetra-O-acetyl-1-O-[1-methyl N-(acetyl)-L-aspart-4-oyl]-alpha-D-glucopyranose (4alpha) and 1,3,4,6-tetra-O-acetyl-2-O-[4-methyl N-(acetyl)-L-aspart-1-oyl]-D-glucopyranose (6) which were also prepared by definitive methods. On the other hand, deprotection of 1beta gave isomerically pure 2beta which was converted into the peracetylated ester derivative 4β an explanation for the differences in aglycon isomeric purity of 2alpha and 2beta is given. Hydrogenolysis of 7beta under the above conditions led to intermolecular transesterification with scission of the C-1 ester bond to give 1-(2-methoxyethyl) L-aspartic acid and D-glucose. Catalytic hydrogenation of 7alpha and 7beta, performed in the presence of trifluoroacetic acid, afforded 1-O-(L-alpha-aspartyl)-alpha- and -beta-D-glucopyranoside trifluoroacetate salts (11alpha and 11beta), respectively. The structure of 11beta was established by successive conversion into 2,3,4,6-tetra-O-acetyl-1-O-[4-methyl N-(acetyl)-L-aspart-1-oyl]-beta-D-glucopyranose (5beta) which was also prepared by definitive methods. Analogous treatment of 11alpha gave the N-acetyl derivative 12 which underwent 1 leads to 2 acyl migration during esterification with diazomethane to give the N-acetyl methyl ester derivative 10; acetylation of 10 afforded 6.
- Valentekovic,Keglevic
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