Studies on lysophospholipases III. The complete purification of two proteins with lysophospholipase activity from beef liver

Abstract

1. 1. Two proteins with lysophospholipase activity (EC 3.1.1.5), provisionally denoted lysophospholipase I and lysophospholipase II, were found to be present in beef liver homogenates. These lysophospholipases were well separated during DEAE—cellulose chromatography of delipidated beef liver extracts.

2. 2. Lysophospholipase I and lysophospholipase II required a 3590-fold and a 770-fold purification, respectively, in order to obtain homogeneous preparations.

3. 3. The molecular weights of lysophospholipases I and II were estimated to be about 25 000 and 60 000, respectively. Isoelectric points of 5.2 and 4.5 were measured for the two enzymes.

4. 4. In accordance with previous observations on beef pancreatic lysophospholipase, both lysophospholipases from beef liver exhibited general esterolytic properties in that compounds like tributyrin and p-nitrophenylacetate were also hydrolysed. Evidence is provided indicating that the hydrolysis of these compounds is an intrinsic property of the beef liver lysophospholipases.

5. 5. Highly purified non-specific carboxylesterases (EC 3.1.1.1) were found to be essentially inactive against 1-acyllysophosphatidylcholine.