The formation of choline from S-[Me-14 C] adenosylmethionine in isolated microsomes has
been studied. The enzyme system was found to be inhibited by mercury compounds,
showing that free sulfhydryl groups are requied. Choline formation is inhibited by BAL and
by mercaptoethanol. This inhibition is due to the presence of an enzyme system in
microsomes catalyzing a transmethylation from S-adenosylmethionine to these
“nonphysiological” sulfhydryl compounds. S-adenosylethionine inhibits choline formation as …