The estimation of phospholipase A activity in aqueous systems

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Abstract
A study has been made of the enzymic degradation of ovolecithin by snake-venom phospholipase A in a number of different buffered media. A system containing 2:4:6-collidine buffer and ether is described in which the conversion of lecithin into lysolecithin proceeds rapidly to completion. The course of the reaction was followed by determining the decrease in acyl ester bonds. The substrate itself was used as a standard in the method described. The effect of pH, venom concentration and substrate concentration on the activity of snake-venom phospholipase A has been investigated. A Michaelis constant for the enzymic reaction was determined. The optimum concentration of added Ca2+ ions in the reaction system was 0.5 m[image]. The aqueous assay system has been adapted to the detection and estimation of phospholipase A activity in a crude tissue preparation (commercial pancreatin). It was calculated on a dry weight basis that the phospholipase A activity of the venom of the cottonmouth moccasin was 17,000 times as great as that of pancreatin.