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The enzymic degradation of ovolecithin and certain other phosphoglycerides in ethereal solution by snake-venom phospholipase A is stimulated by Ca2+ ions. The optimum Ca2+ ion concentration varies between 40 and 80 /LM, when the lecithin concentration varies between 1*3 and 3-3 mM. 2. The phospholipase A activity of moccasin venom is inhibited by ethylenediaminetetraacetic acid and by Zn2+ and CU2+ ions, but not by iodoacetate or p-chloromercuribenzoate. 3. All the natural and synthetic L-c-lecithms studied lost one ester group/molecule of substrate in the presence of the enzyme. SynthetiC DL-Xlecithins lost only 0.5 mole of ester/molecule of substrate, whereas synthetic ,-lecithins did not undergo any enzymic hydrolysis. 4. Egg phosphatidylethanolamine was degraded by phospholipase A when the ethereal solution was adjusted to pH 7-0, and there is some evidence for the breakdown of phosphatidylserine and ethanolamine plasmalogen.

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1. In barley, beta-glucosidase and beta-galactosidase are separate enzymes. The former also displays beta-d-fucosidase activity. 2. In the limpet, Patella vulgata, beta-glucosidase activity is associated with the beta-d-fucosidase, previously shown to be a separate entity from the beta-galactosidase also present. 3. Almond emulsin presents all three activities as a single enzyme. Each is equally inhibited by glucono-, galactono- and d-fucono-lactone. 4. In rat epididymis, there is no significant beta-glucosidase activity, nor is there appreciable inhibition of the beta-galactosidase and beta-d-fucosidase activities of the preparation by gluconolactone.

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