Preparation of guinea pig hepatic microsomes: a comparison of three techniques

Hepatic microsomal preparations by Ca2+-aggregation and gel filtration on Sepharose 2B were compared with the product obtained by differential centrifugation, using liver from adult male guinea pigs. The conventionally-prepared microsomes were translucent and rose-red in color. Those prepared by Ca2+-aggregation were a cream or light pink color whereas the gel-filtered microsomes were opalescent and white. The specific activities of microsomal p-nitroanisole O-demethylase, aniline hydroxylase and nonspecific carboxylase were highest in the Ca2+-aggregated microsomes, intermediate in the gel-filtered preparation and lowest in the conventional microsomes. Electron microscopy revealed vesicular preparations of similar appearance though the Ca2+-aggregated microsomes were larger and contained more aggregates of free ribosomes.