Polymerizable phosphatidylcholines: importance of phospholipid motions for optimum phospholipase A2 and C activity.
Cross-linkable short-chain phosphatidylcholines with thiols at the chain terminus have been synthesized and characterized. These micelle-forming species were used to investigate two water-soluble phospholipases. When reduced, the thiol lipids were excellent substrates for phospholipase A2. Once cross-linked, they became extremely poor substrates. This is consistent with a mechanism in which a key step is the partial extraction of the substrate phosphatidylcholine from an aggregate. In contrast, phospholipase C activity was slightly enhanced if the product diglyceride was tethered to the aggregate through disulfide formation. For this enzyme such a kinetic effect is consistent with the hydrophobic diglyceride biasing the enzyme to the interface.
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Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02167.
Bian
J
J
Roberts
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D004546:Elapid Venoms; D009038:Motion; D010713:Phosphatidylcholines / Q000737:chemistry*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011108:Polymers; D013050:Spectrometry, Fluorescence; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds; D010738:Type C Phospholipases / Q000378:metabolism*
D004546:Elapid Venoms; D010713:Phosphatidylcholines; D011108:Polymers; D013438:Sulfhydryl Compounds; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases