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Ethanolamine plasmalogen methylation by rabbit myocardial membranes

1981; Elsevier BV; Volume: 666; Issue: 2 Linguagem: Inglês

10.1016/0005-2760(81)90108-9

1879-145X

Stanley Mogelson, Burton E. Sobel,

Peroxisome Proliferator-Activated Receptors

Enzymatic methylation of alkenylacylglycerophosphoethanolmine to form alkenylacylglycerophosphocholine was observed in rabbit myocardial membranes, and was compared to the corresponding methylation sequence for diacyl substrates. Membranes were incubated with S-adenosyl-l-[methyl-3H]methionine and assayed for incorporation of radioactivity into selected lipids. The rate of incorporation of methyl groups into diacylglycerophosphocholine exceeded that for alkenylacylglycerophosphocholine, 12.0 ± 3.6 vs. 3.9 ± 0.7 pmol product fonned/ mg per h (mean ± S.D.), even when normalized for ethanolamine substrate concentration (5.7 ±1.6 vs. 1.8 ± 0.4 pmol CH3 incorporated/μmol diradylglycerophosphoethanolamine). Rabbit myocardial phospholipid methyltransferase activity is optimal at basic pH for each substrate, is moderately stimulated by added Ca2+ or Mg2+ and is completely inhibited by S-adenosylhomocysteine. An apparent Km of 0.2 mM for S-adenosylmethionine applies to diacyl- and alkenylacylglycerophosphocholine formation; at low concentrations of methyl donor (0.003 mM), the monomethylated products accumulate.