Kinetics and equilibria of S‐nitrosothiol—thiol exchange between glutathione, cysteine, penicillamines and serum albumin

FEBS Letters

Ketterer, Brian²  Meyer, David J.²  Coles, Brian²  Özer, Nazmi¹  Kramer, Harry² 

[1] Department of Biochemistry, School of Medicine, Hacettepe University, 06100 Ankara, Turkey;Cancer Research Campaign Molecular Toxicology Research Group, Department of Biochemistry and Molecular Biology, University College, Windeyer Building, Cleveland Street, London, W1P 6DB, UK

关键词: Nitrosothiol;    Nitric oxide;    Thiol;    Nitrosothiol exchange;    RSNO;    S-nitrosothiol;    SNO—SH exchange;    S-nitroso-thiol-thiol exchange;    GSH;    glutathione;    GSNO;    S-nitroso-glutathione;    cySNO;    S-nitroso-cysteine;    penSNO;    S-nitroso-penicillamine;    SNAP;    S-nitroso-N-acetyl-penicillamine;    albSNO;    S-nitroso-human serum albumin;   

DOI  :  10.1016/0014-5793(94)00429-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The kinetics and equilibria of S-nitrosothiol-thiol (SNO—SH) exchange reactions were determined using differential optical absorption. At pH 7.4 and 37°C, k ₂ values ranged from 0.9 M⁻¹ · s⁻¹ for the reaction between S-nitroso-glutathione (GSNO) and N-acetyl-penicillamine, and up to 279 M⁻¹ · s⁻¹ for the exchange between S-nitroso-penicillamine (penSNO) and GSH. SNO—SH exchange involving GSH/GSNO and cysteine/cySNO was relatively rapid, k ₂ approx. 80 M⁻¹ · s⁻¹ with an equilibrium constant slightly in favour of GSNO. GSNO was strongly favoured in equilibrium with penSNO, k _eq 0.0039. In the case of SNO—SH exchange between S-nitroso human serum albumin (albSNO) and GSH or cysteine k ₂ values were 3.2 and 9.1 M⁻¹ · s⁻¹, respectively. The results show that the initial rate of SNO—SH exchange between physiological albSNO (7 μM) and venous plasma levels of GSH and cysteine is very slow, < 1%/min. On the other hand, if a nitrosothiol such as cySNO were to enter a cell, it would be rapidly converted to GSNO (43%/s).

【 授权许可】

Unknown