Secreted phospholipases enzymes group

Group I secreted PLA. This group of phospholipases contains group lA enzymes such as those from cobra and krait venom, while the IB enzymes are the... 

I various subcellular locations within eukaryotic cells. Some of these enzymes are specific for particular polar head-groups others are nonspecific. Phospholipase A2 is a major component of snake venom (cobra and rattlesnake) and is partially involved in the deadly effects of these venoms. Because of the high concentration of phospholipase A2 in these venoms, this enzyme has been studied intensively. The pancreas is also rich in phospholipase A2, which is secreted into the intestine for digestion of dietary phospholipids. 

The inactivation of PAF also occurs in two steps (Figure 25-3). Initially, the acetyl group of PAF is removed by PAF acetylhydrolase to form lyso-PAF this enzyme, a group VI phospholipase A2, exists as secreted and intracellular isoforms and has marked specificity for phospholipids with short acyl chains at the sn-2 position. Lyso-PAF is then converted to a l-O-alkyl-2-acyl-glycerophosphocholine by an acyltransferase. 

Pancreatic enzymes a group of at least 12 digestive enzymes, including some of the most investigated of all enzymes Autolysis of the pancreas does not occur, because the proteolytic enzymes, trypsin, chymo-trypsin A and B, elastase and carboxypeptidase A and B, and phospholipase A2 are synthesized and stored in the pancreas as inactive zymogens. The other P. e. require effectors for optimal activity, which are present in the duodenum. Trypsin inhibitors in the pancreatic tissue and secretion afford additional protection against proteolytic destruction by active P.e. With the exception of cholesterol esterase (M, 400,000), the M, of P.e. lie between 13,700 (ribonu-clease) and 50,000 (a-amylase). 

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