ATP-dependent Lon protease from maize mitochondria -: comparison with the other Lon proteases

ATP-dependent protease has been identified in the mitochondrial matrix of Zea mays L. Sachara. Enzyme has been purified 139-fold. Enzyme digests [(14)C]-methylated beta-casein yielding TCA-soluble peptides and needs ATP and Mg(2+) ions for its activity and stability. Inhibitory profile corresponds to those of ATP-dependent serine proteases of Lon (La) family. Optimal pH is 8.5-9.0 and optimal temperature 40-45degreesC, suggesting the heat shock character of the enzyme. Basic enzymatic characteristics of maize mitochondrial protease are similar to those of corresponding Lon protease from rat liver and yeast mitochondria and of E. coli protease La. ATP-dependent protease from maize mitochondria seems to be a heptamer with considerably less stability than other mitochondrial Lon proteases.