A preparative method for isolation of peroxisomes from rat kidney

A new method for the isolation of peroxisomes from rat kidney cortex is described. The L fraction obtained according to Wattiaux-De Coninck et al. (1965) was layered on a discontinuous Nycodenz gradient (density = 1.15-1.21 g/ml) and then centrifuged in a fixed angle rotor for 45 min. at 136,000 g. On the basis of the morphological and biochemical analysis, the fraction recovered at the bottom of the tube was composed mainly by peroxisomes enriched in fatty acyl beta-oxidation system, whereas lower enrichment was found for other peroxisomal marker enzymes. Negligible contamination by mitochondria (marker enzyme cytochrome oxidase), lysosomes (marker enzyme acid phosphatase) and microsomes (marker enzyme NADPH cytochrome c reductase) was found.