ENDOGENOUS UBIQUINOL PREVENTS PROTEIN MODIFICATION ACCOMPANYING LIPID-PEROXIDATION IN BEEF-HEART SUBMITOCHONDRIAL PARTICLES

This article is a study of the relationship between lipid peroxidation and protein modification in beef heart submitochondrial particles, an d the protective effect of endogenous ubiquinol (reduced coenzyme Q) a gainst these effects, ADP-Fe3+ and ascorbate were used to initiate lip id peroxidation and protein modification, which were monitored by meas uring TEARS and protein carbonylation, respectively. Endogenous ubiqui none was reduced by the addition of succinate and antimycin. The param eters investigated included extraction and reincorporation of ubiquino ne, and comparison of the effect of ubiquinol with those of various an tioxidant compounds and enzymes, as well as the iron chelator EDTA. Un der all conditions employed there was a close correlation between lipi d peroxidation and protein carbonylation, and the inhibition of these effects by endogenous ubiquinol. SDS-PAGE analysis revealed a differen tial effect on individual protein components and its prevention by ubi quinol. Conceivable mechanisms behind the observed oxidative modificat ions of membrane phospholipids and proteins and of the role of ubiquin ol in preventing these effects are considered.