Perparation and comparative analytical study of cat liver microsomes]

Cat liver homogenates have been fractionated by differential centrifugation. Four particulate fractions (1 000 X g, 10 000 X g, and 145 000 X g) and a supernatant have been obtained. The biochemical composition of these fractions has been established from the assay and distribution pattern of 22 enzymatic and chemical constituents including marker enzymes for mitochondria, lysosomes, peroxisomes, plasma membranes, endoplasmic reticulum, Golgi apparatus and cell sap. The microsomal fraction was characterized by a moderate contamination with large cytoplasmic granules and by a low yield in protein and cholesterol. It contained 50 per cent of Golgi complex and about 40 per cent of plasma membranes. Morphological analysis of subcellular fractions was performed and confirmed biochemical results.