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1.16.1.8: [methionine synthase] reductase

This is an abbreviated version!
For detailed information about [methionine synthase] reductase, go to the full flat file.

Word Map on EC 1.16.1.8

Reaction

2 [methionine synthase]-methylcob(III)alamin + 2 S-adenosyl-L-homocysteine +

NADP+
= 2 [methionine synthase]-cob(II)alamin +
NADPH
+
H+
+ 2 S-adenosyl-L-methionine

Synonyms

EC 2.1.1.135, Methionine synthase cob(II)alamin reductase (methylating), Methionine synthase reductase, MSR, MTRR, NADPH-dependent diflavin oxidoreductase, Reductase, methionine synthase

ECTree

     1 Oxidoreductases
         1.16 Oxidizing metal ions
             1.16.1 With NAD+ or NADP+ as acceptor
                1.16.1.8 [methionine synthase] reductase

Engineering

Engineering on EC 1.16.1.8 - [methionine synthase] reductase

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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A312H
site-directed mutangenesis, mutation of the catalytic residue leads to the kinetic coupling of hydride and interflavin electron transfer, and eliminates the formation of the FAD hydroquinone intermediate, substitution of Ala312 for His in MSR weakens NADP(H) binding as the Km for NADPH and Ki for NADP+ increases 6 and 1.7fold, respectively. NADPH reduction of A312H resembles that of native cytochrome P450 reductase, in that it occurs in two discrete kinetic phases, without the transient formation of the E-FADH2-FMN intermediate
A312Q
site-directed mutangenesis, the catalytic site mutant shows a 2.5fold increased Km and a slightly decreased Ki for the coenzyme FAD
A66G
-
naturally occuring mutation, the MTRR polymorphism leads to a lower affinity for substrate methionine synthase compared to the wild-type enzyme
I22M
-
natural occuring polymorphism, no significant association with bone mineral density or serum osteocalcin level
S175L
-
natural occuring polymorphism, no significant association with bone mineral density or serum osteocalcin level
S698A
site-directed mutagenesis, the mutant shows reduced activity with cytochrome c3+ as substrate compared to the wild-type enzyme, the S698A mutant displays a 6fold reduction in kcat/Km for NADPH
W697F
site-directed mutagenesis, the mutant shows enhanced catalysis, noted by increases in kcat and kcat/Km(NADPH) for steady-state cytochrome c3+ reduction and a 10fold increase in the rate constant associated with hydride transfer, W697F shows a 2.4fold increase in kcat and a 4.8fold increase in catalytic efficiency for NADPH. The mutant displays modest decreases in cytochrome c3+ reduction, a 30fold decrease in the rate of FAD reduction, accumulation of a FADH2-NADP+ charge-transfer complex, and dramatically suppressed rates of interflavin electron transfer
W697H
site-directed mutagenesis, the mutant shows increased activity with cytochrome c3+ as substrate compared to the wild-type enzyme
W697S
site-directed mutagenesis, the mutant shows reduced activity with cytochrome c3+ as substrate compared to the wild-type enzyme
W697Y
site-directed mutagenesis, the mutant shows enhanced catalysis, noted by increases in kcat and kcat/Km(NADPH) for steady-state cytochrome c3+ reduction and a 10fold increase in the rate constant associated with hydride transfer. W697Y shows a 3.4fold increase in kcat and a 6.7fold increase in catalytic efficiency for NADPH. The mutant displays modest decreases in cytochrome c3+ reduction, a 3.5fold decrease in the rate of FAD reduction, accumulation of a FADH2-NADP+ charge-transfer complex, and dramatically suppressed rates of interflavin electron transfer
additional information