[en] We have measured the rate of hydrolysis of liposomes made of DL-alpha-dipalmitoylphosphatidylcholine (DPPC) and L-alpha-dimyristoylphosphatidylcholine by a soluble fraction of highly purified lysosomes isolated from rat liver. Phospholipids are hydrolyzed into lysophospholipids and fatty acids at a rate which is maximal near the temperature characteristic of the gel to liquid crystalline phase transition of the lipid bilayer. This strong influence of the physical properties of the substrate on the enzyme activity suggests a structural analogy between the lysosomal phospholipases of the A type (EC 3.1.1.32 and EC 3.1.1.4) and the pancreatic phospholipase A2.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Vandenbranden, Michel; Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Brussels, 1050, Belgium
De Gand, Georges; Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Brussels, 1050, Belgium
Brasseur, Robert ; Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Brussels, 1050, Belgium
Defrise-Quertain, Fabienne; Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Brussels, 1050, Belgium
Ruysschaert, Jean-Marie; Laboratoire de Chimie Physique des Macromolécules aux Interfaces, Université Libre de Bruxelles, Brussels, 1050, Belgium
Language :
English
Title :
Hydrolysis of phosphatidylcholine liposomes by lysosomal phospholipase A is maximal at the phase transition temperature of the lipid substrate.
