Purification of lysophospholipases. Application of a continuous spectrophotometric assay using thioester substrate analogs.

Purification of lysophospholipases was monitored with four analogs of the natural lysophosphatidylcholine substrate, including two analogs with an acylthioester bond. In all chromatographic procedures employed, peaks of enzymatic activity towards each of the substrates were coincidental; moreover, the ratio of thioester to oxyester hydrolysis rates remained essentially constant over a more than 500-fold purification. These findings strongly support the conclusion that the hydrolysis of the thioester substrates truly reflects the specificity of lysophospholipases, thus allowing the use of a convenient spectrophotometric assay for these enzymes.