N-Acetylcysteine elicited increase in cytochrome c oxidase activity in mice synaptic mitochondria

It has been suggested that thiolic groups are essential for cytochrome c ox idase (COX) activity and other respiratory mitochondrial enzymes, Recent ex periments showed that the thiolic antioxidant N-acetylcysteine (NAC) can pr otect against age-related impairment in COX activity in mice hepatic mitoch ondria. The present paper shows that NAC enhances COX activity in vitro in synaptic mitochondria isolated from young and old mice. The optimum NAC con centration for maximum COX activity was 5 mM in young and 10 mM in old syna ptic preparations. Our data suggest that mitochondrial thiolic groups, whic h are essentials to oxidative phosphorylation, are impaired by aging. (C) 1 999 Elsevier Science B.V. All rights reserved.