Identification and properties of two methyltransferases in conversion of phosphatidylethanolamine to phosphatidylcholine.
Two methyltransferases involved in the methylation of phosphatidylethanolamine to form phosphatidylcholine were demonstrated in a microsomal fraction of bovine adrenal medulla. The first methyltransferase catalyzes the methylation of phosphatidylethanolamine to form phosphatidyl-N-monomethylethanolamine. This enzyme has an optimum pH of 6.5, a low Km for S-adenosyl-L-methionine (1.4 micron), and an absolute requirement for Mg2+. The second methyltransferase catalyzes the two successive methylations of phodphatidyl-N-monomethylethanolamine to phosphatidyl-N,N-dimethylethanolamine and phosphatidylcholine. In contrast to the first methyltransferase, it has an optimum pH of 10 and a high Km for S-adenosyl-L-methionine (0.1 mM) and does not require Mg2+.
D000313:Adrenal Medulla / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008780:Methyltransferases / Q000378:metabolism*; D008861:Microsomes / Q000201:enzymology; D010713:Phosphatidylcholines / Q000096:biosynthesis*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000378:metabolism
D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D012436:S-Adenosylmethionine; D008780:Methyltransferases; D008274:Magnesium