title: Hydrolysis of erythrocyte membrane phospholipids by a preparation of phospholipase C from Clostridium Welchii. Deactivation of (Ca-2+, Mg-2+)-ATPase and its reactivation by added lipids.
abstract: 1. Haemoglobin-free erythrocyte ghosts were prepared in 40 imosM bicarbonate buffer, pH 7.4, containing 1 mM EDTA (40 imosM/l mM EDTA). The ghost preparation was highly permeable on preparation but partially resealed on incubation in media containing Ca-2+. 2. A partially purified preparation of phospholipase C from Clostridum welchii caused an increase in observed Mg-2+-ATPase activity, reflecting a change in the permeability of the ghost to substrate. The phospholipase did not decrease Mg-2+-ATPase even at the highest levels tested. Mg-2+-ATPase activity could therefore be used as a permeability indicatior in these experiments. 3. Both (Ca-2+, Mg-2+)-ATPase activities of the ghosts were progressively lost as a result of the phospholipid hydrolysis induced by phospholipase C. 4. When a haemolysin in the commercial preparation was destroyed by heat-treatment, deactivation of the (Ca-2+, Mg-2+)-ATPase and (Na+, K+, Mg-2+)-ATPases were still observed but permeability changes were greatly reduced. 5. The products of phospholipase action were not inhibitory to the Ca-2+, Mg-2+)-ATPase. 6. Lysolecithin brought about a reactivation of the (Ca-2+, Mg-2+)-ATPase which was superimposed upon permeability changes in the preparation. 7. Reactivation of the (Ca-2+, Mg-2+)-ATPase was brought about by a nonlytic, mixed lipid preparation without significant effect upon permeability. 8. Human erythrocyte (Ca-2+, Mg-2+)-ATPase therefore appears to be an enzyme which responds to perturbation of the lipid environment in the membrane and is a "lipid-dependant" enzyme.
mesh_terms: D000251:Adenosine Triphosphatases / Q000097:blood*; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects / Q000201:enzymology*; D006460:Hemolysin Proteins / Q000494:pharmacology; D006801:Humans; D008055:Lipids / Q000494:pharmacology; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology*; D010740:Phospholipases / Q000378:metabolism*; D010743:Phospholipids / Q000097:blood*; D011188:Potassium / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology
chemical_list: D006460:Hemolysin Proteins; D008055:Lipids; D008244:Lysophosphatidylcholines; D010743:Phospholipids; D012964:Sodium; D010740:Phospholipases; D000251:Adenosine Triphosphatases; D008274:Magnesium; D011188:Potassium; D002118:Calcium