ISSN:
1471-4159
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Medizin
Notizen:
Abstract: Rat brain was found to enzymatically methylate phospholipids to form phosphatidylcholine with S-adenosyl-l-methionine serving as the methyl donor. Methyltransferase activity was localized in the microsomes and synaptosomes. In synaptosomes, at least two enzymes were found to be involved in the formation of phosphatidylcholine. The first methyltransferase which catalyzes the methylation of phosphatidylethanolamine to form phosphatidyl-N-monomethylethanolamine was found to have a pH optimum of 7.5, a low Km for 5-adenosyl-l-methionine and a partial requirement for Mg2. Methyltransferase I is tightly bound to membranes. The second methyltransferase (II) catalyzes the successive methylations of phosphatidyl-N-monomethylethanolamine to phosphatidyl-N, N-dimethylethanolamine and then to phosphatidylcholine. In contrast to methyltransferase I, methyltransferase II has a pH optimum of 10.5, a high apparent Km for S-adenosyl-l-methionine and no requirement for Mg2. Methyltransferase II is easily solubilized by sonication. The highest specific activity for both enzymes was found in the synaptosomal plasma membrane.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1111/j.1471-4159.1980.tb11229.x
