Abstract: Crude zinc chelatase extract prepared from bovine liver and characterized in the present study. The optimal reaction pH and temperature for this enzyme were 6.0 and 60 ℃, respectively, and initial substrate concentration was positively correlated with enzyme activity. This enzyme could catalyze substances with porphyrin ring, especially protoporphyrin disodium. Several activators such as ascorbic acid and ATP could activate its activity in a concentration-dependent manner, whereas Fe2+ and Mg2+ had inhibitory effect on its activity.

Key words: cattle liver, zinc chelatase, enzymatic activity, activator, metal ion