Effects of phospholipids on lysosomal acid lipase purified from rabbit liver

The effects of phospholipids on lysosomal acid lipase purified from rabbit liver were studied. Non-ionic phospholipids such as phosphatidylethanolamine and phosphatidylcholine increased the enzyme activity. However, anionic phospholipids such as phosphatidylserine, phosphatidylinositol, and cardiolipin were ineffective. The acyl chain length and the degree of unsaturation of synthetic phospholipids were also related to the enzyme activity. Among a series of saturated phosphatidylcholines with different acyl chain lengths, 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine was the most effective. Among a series of unsaturated phosphatidylcholines, the enzyme activity increased in parallel with the number of double bonds. The role of lysosomal acid lipase in relation to phospholipids is discussed.