Substrate specificity of two cationic lipases with high phospholipase A1 activity purified from guinea pig pancreas. I. Studies on neutral glycerides.
The substrate specificity of two cationic lipases with high phospholipase A1 activity purified from guinea pig pancreas has been tested towards various neutral glycerides. Triolein hydrolysis proceeded in the absence of di- and monoolein accumulation. Optimal conditions for di- and monoolein hydrolysis included an alkaline pH (9-10), a substrate concentration of 10 mM, and the presence of sodium deoxycholate (12 and 24 mM, respectively). Pancreatic colipase (bovine) had no effect on the activity of the two lipases. The comparison between the rates of hydrolysis of various substrates revealed the following order of decreasing enzyme activity: diolein greater than 1(3)-monoolein greater than tributyrin = triacetin greater than or equal to triolein = 2-monoolein. No hydrolysis of p-nitrophenylacetate and cholesteryloleate could be detected. Using 1-[3H]palmitoyl-2-[14C]linoleoyl-sn-glycerol, both enzymes displayed a strong preference for the 1-position, leading to the accumulation of 2-[14C]linoleoyl-sn-glycerol. Identical activities were found for the two lipases. It is concluded that the two cationic lipases from guinea pig pancreas represent a unique group of lipolytic enzymes different from other previously described enzymes, including classical pancreatic lipase, gastric and lingual enzymes, mold lipases and carboxylesterhydrolase.
D000818:Animals; D003089:Colipases / Q000494:pharmacology; D003840:Deoxycholic Acid / Q000494:pharmacology; D005989:Glycerides / Q000378:metabolism*; D006168:Guinea Pigs; D006736:Horses; D006868:Hydrolysis; D008049:Lipase / Q000378:metabolism*; D010179:Pancreas / Q000201:enzymology*; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054466:Phospholipases A1; D013379:Substrate Specificity; D013997:Time Factors; D014304:Triolein / Q000378:metabolism
D003089:Colipases; D005989:Glycerides; D003840:Deoxycholic Acid; D014304:Triolein; D010740:Phospholipases; D008049:Lipase; D010741:Phospholipases A; D054466:Phospholipases A1