Nitric oxide protects Cu,Zn‐superoxide dismutase from hydrogen peroxide‐induced inactivation

FEBS Letters

Kim, Yu Shin¹  Han, Sanghwa¹ 

[1]Department of Biochemistry, Kangwon National University, Chunchon 200-701, South Korea

关键词: Cu;    Zn-superoxide dismutase;    Hydrogen peroxide;    Nitric oxide;    DHR123;    dihydrorhodamine-1;    2;    3;    DMPO;    5;    5′-dimethyl-1-pyrroline-N-oxide;    DTPA;    diethylenetriaminepentaacetic acid;    EPR;    electron paramagnetic resonance;    SNAP;    S-nitroso-N-acetylpenicillamine;    SOD1;    Cu;    Zn-superoxide dismutase;   

DOI  :  10.1016/S0014-5793(00)01874-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Reaction of Cu,Zn-superoxide dismutase (SOD1) and hydrogen peroxide generates a putative oxidant SOD-Cu²⁺-OH that can inactivate the enzyme and oxidize 5,5′-dimethyl-1-pyrroline-N-oxide (DMPO) to DMPO-OH. In the presence of nitric oxide (NO), the SOD1/H₂O₂ system is known to produce peroxynitrite (ONOO⁻). In contrast to the proposed cytotoxicity of NO conferred by ONOO⁻, we report here a protective role of NO in the H₂O₂-induced inactivation of SOD1. In a dose-dependent manner, NO suppressed formation of DMPO-OH and inactivation of the enzyme. Fragmentation of the enzyme was not affected by NO. Bicarbonate retarded formation of ONOO⁻, suggesting that NO competes with bicarbonate for the oxidant SOD-Cu²⁺-OH. We propose that NO protects SOD1 from H₂O₂-induced inactivation by reducing SOD-Cu²⁺-OH to the active SOD-Cu²⁺ with concomitant production of NO⁺ which reacts with H₂O₂ to give ONOO⁻.

【 授权许可】

Unknown