[Sarcolemmic membrane of various species: data on its enzymatic characterization and chemical composition]

A sarcolemmal enriched fraction, F1, was obtained from the skeletal muscle of rabbit (Oryctolagus cuniculus L.), hamster (Mesocricetus auratus Wateth.), chicken (Gallus gallus L.), frog (Rana ridibunda Seoane), young carp (Carassius carassius L.) and the marine crab (Carcinus maenas L.). In this fraction, 5'-nucleotidase and Na+ + K+-ATPase (as membrane markers) showed higher specific activities than in the three other fractions separated after centrifugation in a discontinuous sucrose gradient; practically, no succinate dehydrogenase activity (a mitochondrial marker) was detected in fraction F1. The ratio "total lipid: protein" was relatively high (near 1.0) and very similar in fraction F1 for the vertebrate species studied; however, the molar ratio "cholesterol: phospholipid" was in the range 0.25--0.57. The following monosaccharides were determined in the fraction F1 from the above mentioned species at increasing concentrations: sialic acid less than Hexosamines less than Hexoses.