Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
The mechanism of cytochrome C oxidase inhibition by nitric oxide
The basic biochemistry of the inhibition of cytochrome oxidase by NO is reviewed. Three possible mechanisms that include the binding of NO to the fully reduced Fea3-CuB site, to the semi-reduced Fea3-CuB site, and to the fully oxidized Fea3-CuB site are confronted with the experimental data. Mathematical models are used to facilitate the analysis and to solve puzzling observations concerning the NO inhibition of cytochrome oxidase. It is concluded that the inhibition of cytochrome oxidase by NO is mixed, having both competitive and uncompetitive components, but under physiological electron flows the competitive component is largely predominant. The physiological and pathological relevance of this inhibition is briefly discussed.