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Results show that the acidic residue aspartate 120 in the flavin moiety of methylenetetrahydrofolate reductase modulates flavin reactivity and participates in the binding of folate and catalysis of its reduction. Glutamate 18 serves as a catalyst for 5-iminium cation formation and required for the reduction of CH(sub)2-hydrogen(sub)4 folate.

Results show that the reductive and oxidative half-reactions of methylenetetrahydrofolate reductase from Escherichia coli proceed at rates sufficient to establish the ping-pong Bi-Bi mechanism for the enzyme kinetics. Data indicate that the enzyme can serve as a model to study mechanistic aspects of oxidoreductase reactions.

Research was conducted to examine the purification and properties of NADH-dependent 5,10-methylenetetrahyrofolate reductase (MetF) from Escherichia coli. The MetF protein was purified to homogeneity and was revealed to be a flavoprotein capable of catalyzing the NADH-linked reduction of CH2-H4folate to CH3-H4folate with no additional enzymes or cofactors. Results demonstrate that the purified enzyme is a tetramer but that it loses its NADH-flavine adenine dinucleotide factor when diluted.

Research was conducted to compare the binding properties of the full-length HMG domain protein human SRY (hSRY) and its high-mobility group (HMG) domain The human SRY protein was determined and purified from Escherichia coli MC15 region while unlabled competitor DNAs were titrated in binding reaction mixtures. Results indicated that the full-length hSRY characterized a higher DNA binding specificity than the hSRY-HMG domain. They also suggested that DNA bending may play an important role in the biological function of hSRY in sex discrimination.

A study was conducted to determine the role of Phenylalanine 223 in substrate binding and catalysis. Findings suggested that Leu might be a suitable replacement for Phe223 in the oxidative half-reaction of Escherichia coli MTHFR.

Study was conducted to show a new syn intramolecular pathway in the elimination of acetic acid from beta-acetoxy esters and thioesters as a part of a comprehensive investigation of electronic effects on the stereochemistry of based-catalyzed 1,2-elimination reactions. Results show that more acidic thioester substrates do not produce an increased amount of syn stereoselectivity even though their elimination reactions are at the Elcb interface.

A study is carried out on Escherichia coli methylenetetrahydrofolate reductase (MTHFR) that catalyzes the NADH-linked reduction of 5,10-methylenetetrahydrofolate (CH2-H4folate) to 5-methyletetrahydrofolate [CH3-H4folate] by using flavin adenine dinucleotide (FAD) as cofactor. Asp120's influence on the redox properties of the enzyme-bound FAD is discussed.

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydofolate (CH2-H4folate) to 5-methyltetrahydrofolate (CH3-H4folate). The enzyme employs a noncovalently-bound flavin adenine dinucleotide (FAD), which accepts reducing equivalents from NAD(P)H and transfers them to CH2-H4folate. The reaction provides the sole source of CH3-H4folate, which is utilized by methionine synthase in the synthesis of methionine from homocysteine. MTHFR plays a key role in folate metabolism and in the homeostasis of homocysteine; mutations in the enzyme lead to hyperhomocyst(e)inemia. A common C677T polymorphism in MTHFR has been associated with an increased risk for the development of cardiovascular disease, Alzheimer's disease, and depression in adults, and of neural tube defects in the fetus. The mutation also confers protection for certain types of cancers. This review presents the current knowledge of the enzyme, its biochemical characterization, and medical significance.