- 15N NMR and electronic properties of S-nitrosothiols.
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Investigation of the 15N NMR of S-nitrosothiols showed that primary and tertiary RSNOs have distinct 15N chemical shifts around 730 and 790 ppm, respectively. Using 15N NMR technique, the equilibrium constant of NO transfer between SNAP and GSH was found to be 0.74. For primary RSNOs, linear relationships exist among 15N NMR chemical shifts, reduction potentials, and the pK(a)s of their parent thiols.
- Wang,Hou,Zhang,Ksebati,Xian,Cheng,Wang
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- Equilibrium and kinetics studies of transnitrosation between S-nitrosothiols and thiols
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Using UV-vis spectrometrical measurements, equilibrium constants for NO transfer between S-nitroso-N-acetyl-penicillamine (SNAP) and different thiols as well as kinetic data for NO transfer from S-nitroso bovine serum albumin (BSANO) to thiols have been obtained. NO transfer from SNAP to other primary/secondary thiols are thermodynamically favorable, whereas other S-nitrosothiols exhibit similar NO transfer potential. The obtained Gibbs free energy, enthalpy and entropy data indicated that NO transfer reactions from SNAP to four thiols are exothermic with entropy loss. The kinetic behavior of BSANO/RSH transfer can be related to both the acidity of sulfhydryl group and the electronic structure in thiol.
- Wang, Kun,Wen, Zhong,Zhang, Wei,Xian, Ming,Cheng, Jin-Pei,Wang, Peng George
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p. 433 - 436
(2007/10/03)
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- Synthesis and Characterisation ot Diastereomeric (4S)-3-Acetyl-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic Acids
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The condensation of aromatic aldehydes 1 and D-penicillamine (2) in aqueous methanol gives (4S)-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic acids 3 with alternating diastereoselectivity in position 2.Acetylation of the products with acetic anhydride in pyridine or in water gives rise to (2S,4S)-3-acetyl-2-aryl-5,5-dimethyl-4-thiazolidinecarboxylic acids 5.Use of a HCl/dioxane system in the reaction of N-acetyl-D-penicillamine (6) with aldehydes made possible the effective preparation of (2R,4S) compounds 8.The diastereommeric compounds 5 and 8 were characterized by (1)H- and (13)C-NMR data and optical rotation and CD.The results were compared with those compiled from the already synthesized diastereomeric (4R)-3-acetyl-2-aryl-4-thiazolidinecarboxylic acids.
- Gyoergydeak, Zoltan,Kajtar, Judit,Kajtar, Marton,Kajtar-Peredy, Maria
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p. 281 - 286
(2007/10/02)
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- Studies Related to Thietan-2-ones. Part 1. Conversion of D-Penicillamine into DL-2-Methylpenicillamine using Thietan-2-one-based Chemistry
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A series of N-substituted derivatives of (3R)-3-amino-4,4-dimethylthietan-2-one has been prepared from D-penicillamine (3).Attempts to effect the methylathion at position 3 of the N-acetyl (7a), N,N-diacetyl (12), N-benzyloxycarbonyl (7b), or N-(p-nitrobenzylidene) derivative (15a) were unrewarding.Although the N-benzylidene and N-furfurylidene derivatives (15b) and (15c) were successfully methylated at position 3 by using iodomethane and potassium t-butoxide in tetrahydrofuran (THF), best results were achieved by treating the N-(2-hydroxy-1-naphthylmethylene) derivative (15d) with iodomethane and sodium hydride in N,N-dimethylformamide.Cleavage of the imine linkage of the methylated derivatives of the thietanones (15c) and (15d), i.e. compounds (19b) and (19c), was effected by using, respectively, toluene-p-sulphonic acid in THF and dilute hydrochloric acid in acetone.The derived salts of (3RS)-3-amino-3,4,4-trimethylthietan-2-one, i.e. (21a) and (21b), underwent hydrolysis in boiling water to give the corresponding salts of DL-2-methylpenicillamine, i.e. (22a) and (22b).
- Al-Zaidi, Shakir M.R.,Crilley, Martine M. L.,Stoodley, Richard J.
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p. 2259 - 2266
(2007/10/02)
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