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Nitric oxide protects Cu,Zn‐superoxide dismutase from hydrogen peroxide‐induced inactivation
Author(s) -
Kim Yu Shin,
Han Sanghwa
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)01874-3
Subject(s) - peroxynitrite , chemistry , hydrogen peroxide , superoxide dismutase , nitric oxide , superoxide , enzyme , bicarbonate , sod1 , biochemistry , catalase , radical , organic chemistry
Reaction of Cu,Zn‐superoxide dismutase (SOD1) and hydrogen peroxide generates a putative oxidant SOD‐Cu 2+ ‐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/H 2 O 2 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 H 2 O 2 ‐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‐Cu 2+ ‐OH. We propose that NO protects SOD1 from H 2 O 2 ‐induced inactivation by reducing SOD‐Cu 2+ ‐OH to the active SOD‐Cu 2+ with concomitant production of NO + which reacts with H 2 O 2 to give ONOO − .