Microsomal phosphatidylethanolamine methyltransferase: Effect of altered S-adenosylmethionine-S-adenosylhomocysteine ratios in rat liver

Abstract 1. 1. The enzymatic activity of the phosphatidylethanolamine methyltransferase which catalyzes the conversion of phosphatidylethanolamine (PtdEtn) phosphatidylcholine (PtdCho) and the concentration of S -adenosylmethionine (AdoMet) and S -adenosylhomocysteine (AdoHcy) have been determined in liver of rats during fasting and following the administration of bromobenzene, a compound which depletes the liver of SH compounds. 2. 2. AdoHcy is a product of all AdoMet reactions and is a potent competitive inhibitor of phosphatidylethanolamine methyltransferase. 3. 3. The concentration of AdoMet-AdoHcy in the liver varies directly to the enzymatic activity of phosphatidylethanolamine methyltransferase during starvation and following the administration of bromobenzene.