Dependence of gel-filtered guinea pig hepatic microsomes on a soluble factor for maximum mono-oxygenase activities

Guinea pig hepatic microsomes were prepared by gel filtration on Sepharose 2B. A second, peak containing protein and hemoproteins (Hp) markedly increased mono-oxygenase activities when added to the microsomes. Gel filtration of guinea pig microsomes prepared by differential centrifugation revealed possible dissociation during elution from the Sepharose column. Parallel experiments with rat liver were negative.