3.6.1.28 5 - GST-tagged wild type enzyme activity was nearly zero at pH 5.0 3.6.1.28 35 - at pH 5.0: 50% loss of activity after 83 min, at pH 7.6: about 50% loss of activity after 10 min 3.6.1.28 50 - 50% inactivation after 2-4 min 3.6.1.28 50 - rapid inactivation of membrane-associated enzyme 3.6.1.28 55 60 30 min, stable 3.6.1.28 68 - 30 min, 50% loss of activity