Monodehydroascorbate reductase (NADH)

This enzyme belongs to the family of oxidoreductases, specifically those acting on NADH or NADPH with a quinone or similar compound as acceptor. The systematic name of this enzyme class is NADH:monodehydroascorbate oxidoreductase. Other names in common use include NADH:semidehydroascorbic acid oxidoreductase, MDHA, semidehydroascorbate reductase, AFR, AFR-reductase, ascorbic free radical reductase, ascorbate free radical reductase, SOR, MDAsA reductase (NADPH), SDA reductase, NADH:ascorbate radical oxidoreductase, NADH-semidehydroascorbate oxidoreductase, ascorbate free-radical reductase, NADH:AFR oxidoreductase, and monodehydroascorbate reductase (NADH2). This enzyme participates in ascorbate and aldarate metabolism.

In plants, the monodehydroascorbate reductase (MDAR) is an enzymatic component of the glutathione-ascorbate cycle that is one of the major antioxidant systems of plant cells for the protection against the damages produced by reactive oxygen species (ROS). The MDAR activity has been described in several cell compartments, such as chloroplasts, cytosol, mitochondria, glyoxysomes, and leaf peroxisomes.^[1]

References

↑ Leterrier M, et al. (2005). "Peroxisomal monodehydroascorbate reductase. Genomic clone characterization and functional analysis under environmental stress conditions.". Plant Physiol 138 (4): 2111–23. doi:10.1104/pp.105.066225. PMC 1183399. PMID 16055677.

Schulze HU, Schott HH, Staudinger H (1972). "[The isolation and characterization of a NADH: semidehydroascorbic acid oxidoreductase from Neurospora crassa]". Hoppe. Seylers. Z. Physiol. Chem. 353 (12): 1931–42. PMID 4405497.

Oxidoreductases: NADH or NADPH (EC 1.6)

1.6.1: NAD/NADP	NAD(P)⁺ transhydrogenase (Si-specific) NAD(P)⁺ transhydrogenase (Re/Si-specific)

1.6.2: Heme	Methemoglobin reductase NADPH—hemoprotein reductase/Cytochrome P450 reductase NADPH—cytochrome-c2 reductase Leghemoglobin reductase

1.6.3: Oxygen	NADPH oxidase P91-PHOX Neutrophil cytosolic factor 1 Neutrophil cytosolic factor 2 Neutrophil cytosolic factor 4 dual oxidase Dual oxidase 1 Dual oxidase 2

1.6.5: Quinone or similar	NADH dehydrogenase

1.6.6: Nitrogenous group	Trimethylamine-N-oxide reductase

1.6.99: other	NADH dehydrogenase (quinone)

Enzymes

Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Catalytically perfect enzyme Coenzyme Cofactor Enzyme catalysis Enzyme kinetics Lineweaver–Burk plot Michaelis–Menten kinetics

Regulation	Allosteric regulation Cooperativity Enzyme inhibitor

Classification	EC number Enzyme superfamily Enzyme family List of enzymes

Types	EC1 Oxidoreductases(list) EC2 Transferases(list) EC3 Hydrolases(list) EC4 Lyases(list) EC5 Isomerases(list) EC6 Ligases(list)

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