FERROCHELATASE ACTIVITY OF YEAST MITOCHONDRIA

Yeast mitochondrial ferrochelatase activity, measured by using a modified test related to this defined by Pmorra and Jones, is 5 times more important than previously reported. Only one pH maximum has been found at pH 7.6. Km values related to Fe2+ or protoporphyrin are in the order of 10 -5M. Mitochondrial particles depleted of lipids have a slight ferrochelatase activity, which can mostly be restored by addition of phospholipids. Glutathion added to the reaction mixture seems to have a protective role against phospolipids peroxidation. With high Zn2+ concentrations (1O-3M), ferrochelatase catalyses zinc insertion into protoporphyrin. Zn2+ and Co2+, at concentrations similar to Fe2+ (10-4M), inhibit protoheme formation. © 1968.