Aryl mono-oxygencise activity in hepatic microsomes isolated by isoelectric precipitation

The activity of the aryl mono-oxygenase (AMO) system has been compared in hepatic microsomes isolated by precipitation at pH 5.4 and by conventional centrifugation. “Acid” microsomes were shown to contain comparable levels of AMO activity, when measured on a per gram of liver basis, in control and induced rat liver and in human liver. Acid microsomes from control rat liver possess extra nonmicrosomal protein that appears to be cytoplasmic in origin.