Oxidative modifications of cardiac mitochondria and inhibition of cytochrome c oxidase activity by 4-hydroxynonenal.
4-hydroxynonenal (HNE) is a highly toxic product of lipid peroxidation (LPO). Its role in the inhibition of cytochrome c oxidase activity and oxidative modifications of mitochondrial lipids and proteins were investigated. The exposure of mitochondria isolated from rat heart to HNE resulted in a time- and concentration-dependent inhibition of cytochrome c oxidase activity with an IC50 value of 8.3 +/- 1.0 microM. Immunoprecipitation-Western blot analysis showed the formation of HNE adducts with cytochrome c oxidase subunit I. The loss of cytochrome c oxidase activity was also accompanied by reduced thiol group content and increased HNE-lysine fluorescence. Furthermore, there was a marked increase in conjugated diene formation indicating LPO induction by HNE. Fluorescence measurements revealed the formation of bityrosines and increased surface hydrophobicity of HNE-treated mitochondrial membranes. Superoxide dismutase + catalase and the HO* radical scavenger mannitol partially prevented inhibition of cytochrome c oxidase activity and formation of bityrosines. These findings suggest that HNE induces formation of reactive oxygen species and its damaging effect on mitochondria involves both formation of HNE-protein adducts and oxidation of membrane lipids and proteins by free radicals.
Kaplan
Peter
P
Department of Biochemistry, Jessenius Faculty of Medicine, Comenius University, Martin, Slovak Republic. kaplan@jfmed.uniba.sk
Tatarkova
Zuzana
Z
Racay
Peter
P
Lehotsky
Jan
J
Pavlikova
Martina
M
Dobrota
Dusan
D
D000447:Aldehydes / Q000378:metabolism / Q000633:toxicity*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D003576:Electron Transport Complex IV / Q000037:antagonists & inhibitors*; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism; D008929:Mitochondria, Heart / Q000187:drug effects* / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000096:biosynthesis
D000447:Aldehydes; D008563:Membrane Lipids; D017382:Reactive Oxygen Species; D014443:Tyrosine; C007543:dityrosine; D003576:Electron Transport Complex IV; C027576:4-hydroxy-2-nonenal