PURIFICATION OF GUINEA-PIG SMALL-INTESTINAL PEROXISOMES AND THE SUBCELLULAR-LOCALIZATION OF GLUCOSE-6-PHOSPHATE-DEHYDROGENASE

A method for the isolation of highly purified peroxisomes from guinea pig small intestine was developed. This two-stage process involved a r ate-dependent banding of a light-mitochondria lambda-fraction followed by a density-dependent banding of the catalase enriched fractions obt ained from the first step, using a horizontal rotor. Furthermore, the subcellular localization of glucose-6-phosphate dehydrogenase (NADP(+) -dependent) activity in guinea pig small intestine was examined. Analy sis of density-gradient fractions indicated that approximately 3-4% of the cellular NADP(+)-dependent glucose-6-phosphate dehydrogenase acti vity is associated with peroxisomal fractions and that it is localized to the matrix of peroxisomes. It is therefore suggested that a peroxi somal source of NADPH may be utilized by enzyme systems that use NADPH specifically as a reductant.