Utilization of membranous lipid substrates by membranous enzymes. Hydrolysis of sphingomyelin in erythrocyte 'ghosts' and liposomes by the membranous sphingomyelinase of chicken erythrocyte 'ghosts'.

Incubation at 37 degrees C of haemolysed chicken erythrocytes ('chicken erythrocyte ghosts') resulted in hydrolysis of the membrane sphingomyelin, suggesting an activation of a latent sphingomyelinase during the haemolysis procedure. When this incubation was continued for several hours, the entire sphingomyelin of the erythrocyte 'ghosts' was hydrolysed and membranes were obtained that were devoid of sphingomyelin, but had an active sphingomyelinase. Mixing the latter membranes with human erythrocyte 'ghosts' or positively charged liposomes led to hydrolysis of the sphingomyelin in these two membranes. This suggested that, after haemolysis, the activated sphingomyelinase in the membrane of the chicken erythrocyte 'ghosts' could hydrolyse sphingomyelin in its own membrane ('intramembrane utilization') or adjacent membranes ('intermembrane utilization').