On the specificity of rat-liver lysophospholipase

Abstract

1. 1. A study on the specificity of rat-liver lysophospholipase activity (EC 3.1.1.5) revealed that both 1-acyl-sn-glycero-3-phosphorylcholine and 2-acyl-sn-glycero-3-phosphorylcholine are deacylated. From both positional isomers the unsaturated analogs appeared to be degraded at higher rates.

2. 2. Circumstantial evidence is presented indicating that 2-acyl-sn-glycero-3-phosphorylcholine can be attacked directly by this lysophospholipase activity without a prior migration of the fatty acyl constituent.

3. 3. Compounds lacking the free hydroxyl group present in lysophosphatidyl-cholines, e.g. acyl-ethylene glycolphosphorylcholine and 1-acyl-propane diol-3-phosphorylcholine, also fall in the enzyme's range of specificity.

4. 4. Mono-acyl derivatives of sn-glycero-1-phosphorylcholine, sn-glycero-2-phosphorylcholine, as well as sn-glycero-3-phosphorylcholine, were found to be degraded.

5. 5. Inhibition of lysophospholipase activity by various agents exhibited the same effect on the deacylation of both 1-acyl- and 2-acyl-sn-glycero-3-phosphoryl-choline.

6. 6. The degradation of mono-acyl-phosphatidylcholine appeared to be strongly inhibited in the presence of phosphatidylcholine.