title: The action of purified lysophospholipases on microsomal membrane-bound lysophosphatidylcholine.
abstract: Rat liver membranes were labelled by intraperitoneal injection of [Me-14C]choline chloride. Isolated microsomal membranes were briefly treated with pancreatic phospholipase A2 to produce different levels of membrane-bound lysophosphatidylcholine. The hydrolysis of this lysophosphatidylcholine by two purified lysophospholipases from beef liver was studied. The specific activity of enzyme I at saturating membrane concentrations appeared to increase linearly with the lysophosphatidylcholine level in the membranes until the lysoderivative represented 15% of the original phosphatidylcholine. In contrast, the specific activity of enzyme II was independent of the lysophosphatidylcholine level, at least in the range of 4.9-34.0% tested. These different kinetics are discussed in terms of the possible functions of both enzymes in liver.
mesh_terms: D000818:Animals; D002417:Cattle; D007700:Kinetics; D008244:Lysophosphatidylcholines; D008563:Membrane Lipids; D008862:Microsomes, Liver; D010179:Pancreas / Q000201:enzymology; D010740:Phospholipases / Q000378:metabolism*; D051381:Rats; D013552:Swine
chemical_list: D008244:Lysophosphatidylcholines; D008563:Membrane Lipids; D010740:Phospholipases