- Npys-Mediated Elimination Reactions of Alcohols and Thiols: A Facile Route to Dehydroalanine and Dehydrobutyrine Building Blocks
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We report a new and rapid method for side-chain dehydration/dehydrothiolation of serine, threonine, and cysteine building blocks. The method relies on activation with 3-nitro-2-pyridinesulfenyl chloride (Npys-Cl) followed by treatment with base. It is pos
- Olsen, Frank N.,Tsakos, Michail,Poulsen, Thomas B.
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p. 2697 - 2701
(2015/11/27)
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- Ditopic crown ether-guanidinium ion receptors for the molecular recognition of amino acids and small peptides
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A series of ditopic synthetic receptors based on a crown ether-guanidinium ion recognition motif is reported. The compounds show binding affinity to selected amino acids, including important neurotransmitters. The effect of the distance of the ammonium and the carboxylate ion, the rigidity of the spacer, and the use of pre-organized pyrrole- and pyrene-guanidinium groups on binding affinity and selectivity are discussed.
- Sp?th, Andreas,K?nig, Burkhard
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p. 1859 - 1873
(2010/04/06)
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- Catalytic specificity exhibited by p-sulfonatocalix[n]arenes in the methanolysis of N-acetyl-L-amino acids
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Specific acid catalysis of p-sulfonatocalix[n]arenes (n = 4, Calix-S4; n = 6, Calix-S6; n = 8, Calix-S8) was observed in the alcoholysis of N-acetyl-L-amino acids in methanol. The methanolysis rates of basic amino acid substrates (His, Lys, and Arg) were
- Goto, Koichi,Yano, Yoshihiro,Okada, Eiji,Liu, Chin-Wen,Yamamoto, Kiyoto,Ueoka, Ryuichi
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p. 865 - 870
(2007/10/03)
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- Reaction of malondialdehyde-DNA adducts with hydrazines - Development of a facile assay for quantification of malondialdehyde equivalents in DNA
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Malondialdehyde is a ubiquitous product of lipid peroxidation that reacts with DNA to form premutagenic lesions. Principal among them is pyrimido-[1,2-α]purin-10(3H)-one (M1G). M1G has recently been found to be a reactive electrophile in DNA that couples with amines at basic pH or hydroxylamines at neutral pH. We explored the reaction of M1G with hydrazines because of the possibility that the latter could act as bifunctional nucleophiles to strip the malondialdehyde equivalent from DNA. Pentafluorophenylhydrazine reacted rapidly with M1G to form a hydrazone conjugate. This hydrazone was stable at room temperature and did not cyclize to form the corresponding pyrazole. In contrast, phenylhydrazine and benzylhydrazine reacted with M1G to form phenylpyrazole and benzylpyrazole, respectively. Pentafluorobenzylhydrazine reacted rapidly with M1G to form pentafluorobenzylpyrazole and dG in near quantitative yield. This reaction formed the basis for a quantitative assay for the presence of M1G or M1G equivalents in DNA or protein that utilized gas chromatography/negative chemical ionization mass spectrometry. The assay was extended to the oxopropenyl donors, M1A, base propenal, and Nε-3-oxopropenyl-lysine. Analysis of DNA treated with bleomycin demonstrated a linear increase in the level of oxopropenyl groups that plateaued at approximately 1 oxopropenyl group/100 bases at a bleomycin concentration of 200 μM. Parallel analysis of M1G in the samples revealed that this adduct represents a small fraction of the total oxopropenyl units generated in DNA by treatment with bleomycin.
- Otteneder, Michael,Plastaras, John P.,Marnett, Lawrence J.
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p. 312 - 318
(2007/10/03)
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