3.1.7.5 5 7.5 pH 5.0: about 65% of maximal activity, pH 7.0: about 60% of maximal activity, isoenzyme II 694599 3.1.7.5 5 7.5 pH 5.0: about 80% of maximal activity, pH 7.0: about 45% of maximal activity, isoenzyme I 694599