(Methionine synthase) reductase

Class of enzymes [methionine synthase] reductase 1.16.1.8 207004-87-3 0030586 Methionine Synthase Reductase 2QTL.png 2QTL MTRR [Methionine synthase] reductase, or Methionine synthase reductase,While including parentheses is the correct usage since this denotes the substrate being reduced, it is often omitted as omitting parentheses generally cause no confusion. encoded by the gene MTRR, is an enzyme that is responsible for the reduction of methionine synthase inside human body. This enzyme is crucial for maintaining the one carbon metabolism, specifically the folate cycle. The enzyme employs one coenzyme, flavoprotein. Mechanism MTRR works by catalyzing the following chemical reaction: 2 [methionine synthase]-methylcob(I)alamin + 2 S-adenosylhomocysteine + NADP+ 2 [methionine synthase]-cob(II)alamin + NADPH + H+ + 2 S-adenosyl-L-methionine The 3 products of this enzyme are methionine synthase-methylcob(I)alamin, S-adenosylhomocysteine, and NADP+, whereas its 4 substrates are methionine synthase-cob(II)alamin, NADPH, H+, and S-adenosyl-L-methionine. thumb|left|Scavenger Pathway of Methionine Synthase Reductase to Recover Inactivated Methionine Synthase Physiologically speaking, one crucial enzyme in the folate cycle is methionine synthase, which incorporates the coenzyme cobalamin (also known as Vitamin B12). The coenzyme utilizes its cofactor, cobalt to catalyze the transferring function, in which the cobalt will switch between having 1 or 3 valence electrons, dubbed cob(I)alamin, and cob(III)alamin. Over time, the cob(I)alamin cofactor of methionine synthase becomes oxidized to cob(II)alamin, rendering the enzyme inactive. Therefore, regeneration of the enzyme is necessary. Regeneration requires reductive methylation via a reaction catalyzed by (methionine synthase) reductase in which S-adenosylmethionine is utilized as a methyl donor, reducing cob(II)alamin to cob(I)alamin. 0027-8424 95 3059–3064 Leclerc D. A. Wilson R. Dumas C. Gafuik D. Song D. Watkins H. H. Q. Heng J. M. Rommens S. W. Scherer D. S. Rosenblatt R. A. Gravel Cloning and mapping of a cDNA for methionine synthase reductase, a flavoprotein defective in patients with homocystinuria Proceedings of the National Academy of Sciences 1998-03-17 9501215 10.1073/pnas.95.6.3059 6 19694 1998PNAS...95.3059L free Systematic naming This enzyme belongs to the family of oxidoreductases, to be specific those oxidizing metal ion with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is [methionine synthase]-methylcob(I)alamin,S-adenosylhomocysteine:NADP+ oxidoreductase. Other names in common use include methionine synthase cob(II)alamin reductase (methylating), methionine synthase reductase, [methionine synthase]-cobalamin methyltransferase (cob(II)alamin, and reducing). References 1 0027-8424 103 25 9476–9481 Yamada Kazuhiro Roy A. Gravel Tetsuo Toraya Rowena G. Matthews Human methionine synthase reductase is a molecular chaperone for human methionine synthase Proceedings of the National Academy of Sciences 2006-06-20 1480432 10.1073/pnas.0603694103 16769880 2006PNAS..103.9476Y free Olteanu H, Banerjee R 2001 Human methionine synthase reductase, a soluble P-450 reductase-like dual flavoprotein, is sufficient for NADPH-dependent methionine synthase activation J. Biol. Chem. 276 35558–63 11466310 10.1074/jbc.M103707200 38 free Olteanu H, Munson T, Banerjee R 2002 Differences in the efficiency of reductive activation of methionine synthase and exogenous electron acceptors between the common polymorphic variants of human methionine synthase reductase Biochemistry 41 13378–85 12416982 10.1021/bi020536s 45 Biology no Category:EC 1.16.1 Category:NADPH-dependent enzymes Category:Enzymes of unknown structure