Function
Methionine synthase catalyzes the final step in the regeneration of methionine from homocysteine.
Methionine synthase contains the cofactor methylcobalamin (MeB12) and uses the substrates N5-methyl-tetrahydrofolate (N5-mTHF, or levomefolic acid) and homocysteine.
The enzyme works in two steps in a ping-pong reaction. First, methylcobalamin is formed by a methyl group transfer from N5-mTHF with formation of MeB12 and tetrahydrofolate (THF). In the second step, MeB12 transfers this methyl group to homocysteine, regenerating the cofactor cobalamin and releasing the product methionine.
Methionine synthase is the only mammalian enzyme that metabolizes 5-mTHF to regenerate the active cofactor THF. Deficiency in methionine synthase function may be due to genetic mutations, reduced levels of its cobalamin cofactor (vitamin B12), or decreased levels of the enzyme (methionine synthase) reductase (required for the sustained activity of methionine synthase).
Read more about this topic: Methionine Synthase
Famous quotes containing the word function:
“The more books we read, the clearer it becomes that the true function of a writer is to produce a masterpiece and that no other task is of any consequence.”
—Cyril Connolly (1903–1974)
“The information links are like nerves that pervade and help to animate the human organism. The sensors and monitors are analogous to the human senses that put us in touch with the world. Data bases correspond to memory; the information processors perform the function of human reasoning and comprehension. Once the postmodern infrastructure is reasonably integrated, it will greatly exceed human intelligence in reach, acuity, capacity, and precision.”
—Albert Borgman, U.S. educator, author. Crossing the Postmodern Divide, ch. 4, University of Chicago Press (1992)
“Uses are always much broader than functions, and usually far less contentious. The word function carries overtones of purpose and propriety, of concern with why something was developed rather than with how it has actually been found useful. The function of automobiles is to transport people and objects, but they are used for a variety of other purposes—as homes, offices, bedrooms, henhouses, jetties, breakwaters, even offensive weapons.”
—Frank Smith (b. 1928)