2.3.1.39 5 10 about half-maximal activity at pH 5.0, about 80% of maximal activity at pH 10.0 486882 2.3.1.39 6.2 9.8 about half-maximal activity at pH 6.2, about 65% of maximal activity at pH 9.8 285678 2.3.1.39 7.5 8.5 maximal activity 486887