2.1.1.274 additional information - at pH 4.0 and 9.5 the enzyme activity falls to about 20% of the maximal activity 721415 2.1.1.274 5 8 with 80–90% of maximum activity 721415 2.1.1.274 6 9 at pH 6.0 activity is 80% of optimal activity, at pH 8.0 it is 75%, and at pH 9 it is less than 50% 721412 2.1.1.274 7 8 about 90% activity at pH 7.0, about 40% activity at pH 8.0 726129