DETECTION AND CHARACTERIZATION OF PHOSPHOLIPASE-D BY FLOW-INJECTION ANALYSIS

A precisely working automated system for the investigation of phosphol ipases D (PLDs, EC 3.1.4.4) from plant and microbial sources with how injection analysis (FIA) has been developed. The two versions of the F IA setup described are based on the oxidation of choline liberated fro m phosphatidylcholine by PLD action and catalyzed by choline oxidase a nd the chemiluminescence detection of hydrogen peroxide produced by th is reaction. The correlation between this chemiluminescence signal and the PLD activity was linear in the range between 1 and 100 mU/ml PLD. The sampling frequency was 12 samples per hour. This method was used to compare three different PLDs from cabbage and microbial sources wit h respect to their pH optima, temperature stability, effecters, and v/ [S] characteristics. (C) 1997 Academic Press, Inc.