Investigations of the Aortic Phospholipase A, Lipase and Cholesterol Esterase

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Abstract
Effects of different factors on the phospholipase A, lipase and cholesterol esterase activities of the extracts from acetone-butanol powders from pig aortas were estimated using continuous titration method. (2) 70-80% of the total phospholipase activity is contributed by the thermoresistant phospholipase A, whereas the remainder and both the total lipase and total cholesterol esterase activities are brought about by thermolabile enzymes. (3) Optimum pH is 8.0 for the phospholipase A and 8.6 for the thermolabile phospholipase. The lipase has optimum pH at 8.3 and the cholesterol esterase at 8.6. (4) Typical effect of substrate concentrations on phospholipase A and lipase activities is obtained. The optimum concentration of a substrate at 0.8-1.0 X 10^-3 mol/l for cholesterol esterase activity is observed. (5) Typical curves of reaction velocity for the 3 enzymes are obtained. (6) Calcium, sodium and potassium ions within the concentration range of 10^-3 mol/l decrease the phospholipase A, lipase and cholesterol esterase activities. (7) The cholesterol esterase activity is enhanced by sodium taurocho late but depressed by sodium deoxycholate at 10^-3 mol/l concentration range of either. Both the lipase and phospholipase A activities are markedly decreased by the bile acid salts. (8) The 3 enzymes are inhibited by diisopropylfluorophosphate.

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