Abstract
The formation of choline from S-[ Me- 14C]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 a competitive inhibitor of S-adenosylmethionine. Choline formation is stimulated by the addition of d, l(N,N-dimethyl)disteary l- α-cephalin in vitro, but not by dipalmitoyl-α-cephalin. The incorporation of the first methyl group is found to be the rate limiting step in choline biosynthesis. The choline-synthesizing enzyme system is found in several tissues of the rat and in the liver of 8 different animal species investigated. These results are discussed in relation to choline biosynthesis in vivo.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
