title: Effects of lipolytic enzymes on the photochemical activities of spinach chloroplasts.
abstract: 1. Spinach class II chloroplasts were treated with purified potato lipolytic acyl-hydrolase and venom phospholipase A2, and their lipid degradations and the effects on the photochemical activities were followed. 2. Potato lipolytic enzyme hydrolyzed monogalactosyldiacylglycerol at a faster rate than phospholipids such as phosphatidylglycerol and phosphatidylcholine. The treatment caused a rapid decrease of Photosystem I activity, and a less change of Photosystem II activity. 3. Venom phospholipase A2 which preferentially hydrolyzed phosphatidylglycerol, caused a rapid decrease of Photosystem II activity and only a slight decrease of photosystem I activity. 4. Potato enzyme and phospholipase A2 degraded the membrane lipids of glutaraldehyde-fixed chloroplasts at a rather slightly higher rate than those of non-treated chloroplasts. 5. The results suggested a possible correlation between monogalactosyldiacylglycerol degradation and decay of Photosystem I activity and between phosphatidylglycerol degradation and decay of Photosystem II activity. A possible mechanism is discussed.
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D006867:Hydrolases / Q000494:pharmacology*; D006868:Hydrolysis; D008055:Lipids / Q000032:analysis; D010740:Phospholipases / Q000494:pharmacology*; D010777:Photochemistry
chemical_list: D005230:Fatty Acids, Nonesterified; D008055:Lipids; D006867:Hydrolases; D010740:Phospholipases