Kinetics of the inhibition of mitochondrial respiration by NO

FEBS Letters

Matthias, Anita¹  Bronnikov, Gennady¹  Koivisto, Ari¹  Nedergaard, Jan¹ 

[1] The Wenner-Gren Institute, The Arrhenius Laboratories F3, Stockholm University, S-106 91 Stockholm, Sweden

关键词: Nitric oxide;    Oxygen;    Cytochrome c oxidase;    Hypoxia;    Non-shivering thermogenesis;    Brown fat mitochondria;   

DOI  :  10.1016/S0014-5793(97)01258-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The kinetics of the inhibition of mitochondrial respiration by NO was examined in isolated mitochondria (here obtained from rat brown adipose tissue). The K _i of NO for the inhibition was ∼27 nM; the IC₅₀ of NO increased in proportion to the square of an increase in O₂ tension. The K _m of O₂ for respiration was ∼16 μM; in the presence of NO, the dependence of respiration on O₂ tension had a Hill coefficient of ∼2. The unusual kinetics is probably related to the ability of cytochrome c oxidase to use 2 NO or 1 O₂ as electron acceptor. The interaction between NO and O₂ in the control of respiration could be described by the formula V _O2(O₂, NO)=V _O2max·([O₂]²/((16 μM·(1+[NO]/27 nM))²+[O₂]²)). Thus, the kinetics is such that respiration in the presence of physiological levels of NO is very sensitive to decreasing O₂ tension.

【 授权许可】

Unknown