Biosynthesis and Biochemical Roles
Homocysteine is not obtained from the diet. Instead, it is biosynthesized from methionine via a multi-step process. First, methionine receives an adenosine group from ATP, a reaction catalyzed by S-adenosyl-methionine synthetase, to give S-adenosyl methionine (SAM). SAM then transfers the methyl group to an acceptor molecule, (i.e., norepinephrine as an acceptor during epinephrine synthesis, DNA methyltransferase as an intermediate acceptor in the process of DNA methylation). The adenosine is then hydrolyzed to yield -homocysteine. -Homocysteine has two primary fates: conversion via tetrahydrofolate (THF) back into -methionine or conversion to -cysteine.
Read more about this topic: Homocysteine
Famous quotes containing the word roles:
“There is a striking dichotomy between the behavior of many women in their lives at work and in their lives as mothers. Many of the same women who are battling stereotypes on the job, who are up against unspoken assumptions about the roles of men and women, seem to accept—and in their acceptance seem to reinforce—these roles at home with both their sons and their daughters.”
—Ellen Lewis (20th century)