This material causes defection of methionine synthase
that converts homocysteine to methionine and there for decreases concentration of homocysteine .
6] insufficiency result in increased homocysteine concentrations because they are cofactors for methionine synthase
and cystathionine synthase, respectively.
Folate is required for methionine synthase
to convert dangerous homocysteine into the amino acid methionine, thus preventing the buildup of homocysteine.
The 5-MTHF generated then can be used in the remethylation of homocysteine (Hcy) to methionine, which is catalyzed by methionine synthase
One is methionine synthase
(MS), by which Hcy react with 5-methyl tetrahydrofolate (5mTHF) to become Met.
Methylcobalamin together with folate plays a role as a coenzyme for methionine synthase
which catalyses the conversion of homocysteine to methionine, which is required for the formation of S-adenosylmethionine, a universal donor for almost 100 different substrates, including DNA, RNA, hormones, proteins and lipids1.
The genes they have looked at are involved in the intracellular transport (reduced folate carrier 1 or RFC1), and conversion ([gamma] glutamyl hydrolase or GGH) of methotrxate, metabolism of purine and pyrimidine (methylenetetrahydrofolate reductase or MTHFR, thymidylate synthase or TS, methionine synthase
or MS, serine hydroxymethyltransferase I or SHMT 1 , aminoimidazol carboxamide ribinucleotide transformylase or ATIC, methionine synthase
reductase or MTRR) and efflux of the drug (multidrug resistance protein 1 or MDR1).
Objective: In this study, we investigated whether methionine synthase
(MTR) A2756G and methionine synthase
reductase (MTRR) A66G gene polymorphisms were related with infertility.
In most tissues, the remethylation of homocysteine is catalyzed by methionine synthase
(MS), which uses [B.
catalyzes the transfer of the methyl group of 5-methyltetrahydrofolate to homocysteine via a methylcobalamin intermediate with cycling of cobalamin between the +1 valency state cobalamin and the +3 valency state cobalamin [1,2].
NO has been reported to inhibit methionine synthase
activity in vitro (37-39), and it might be expected to bind to the cobalt in cobalamin because, first, NO binds tightly to the iron in heme (40); second, ferrous heme and cbl(III) are isoelectronic; and third, in both heme and cobalamin, the metal ion is coordinated to four in-plane nitrogen atoms of a tetrapyrrole ring and has two out-of-plane ligands (41).
Seven functional polymorphisms and six genes in the folate homocysteine pathway were considered: 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C > T, MTHFR 1298A > C, cystathionine [beta] synthase (CBS) 844ins68, methionine synthase
(MTR) 2756A > G, methionine synthase
reductase (MTRR) 66A > G, thymidylate synthase (TYMS) 1494del6, and dihydrofolate reductase (DHFR) c.