phospholipase D

sujoy ghosh ghoshs at
Sun Sep 10 13:55:33 EST 1995

The transphosphatidylation reaction catalyzed by PLD in the presence of 
alcohols is not a normal physiological event. The normal reaction 
catalyzed by PLD is a hydrolysis reaction where water is used instead of 
the alcohols. In this reaction, phosphatidylcholine is broken down to 
phosphatic acid and choline.  Thus phosphatidic acid (PA) is the natural 
product derived from PC by action of PLD. PA cannot be directly 
converted to phosphatidylcholine ; it is further degraded to 
diacylglycerol (assuming the phospholipid had a diacyl content) by the 
action of an enzyme called phosphatidate phosphohydrolase. The DG can 
then react with cytidine-diphospho-choline (CDP-choline) to make 
phosphatidylcholine (and cytidine monophosphate). This condensation of 
diacylglycerol with CDP-choline is catalyzed by an enzyme called choline 
phosphotransferase (CPT). SO the net reaction is:
PC + H20 =  PA + choline (catalyzed by PLD)
PA + H20 = DG  + phosphate (catalyzed by phosphatidate phosphohydrolase)
DG + CDP-choline = PC + CMP (catalyzed by choline phosphotransferase)
Hope this helps

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