3.1.1.31 5 8.2 approx. 40% of maximal activity at pH 5.2, approx. 20% of maximal activity at pH 8.2 649488 3.1.1.31 5.7 8.5 approx. 50% of maximal activity at pH 5.8, approx. 60% of maximal activity at pH 8.0 649488 3.1.1.31 5.8 7.5 pH 8, spontaneous hydrolysis drastic increases above 80874 3.1.1.31 5.8 7.5 spontaneous hydrolysis of 6-phospho-D-glucono-1,5-lactone 80870