Oxido-reductases

A substantial fraction of the named enzymes are oxido-reductases, responsible for shuttling electrons along metabolic pathways that reduce carbon dioxide to sugar (in the case of plants), or reduce oxygen to water (in the case of mammals). The oxido-reductases that drive these processes involve a small set of redox active cofactors , that is, small chemical groups that gain or lose electrons. These cofactors include iron porjDhyrins, iron-sulfur clusters and copper complexes as well as organic species that are ET active. 

OXIDO-REDUCTASES FROM GENETICALLY ENGINEERED YEAST STRAINS AND THEIR BIO ANALYTICAL APPLICATION... 

NADPH quinone oxido-reductase 1 Pro187Ser variant occurring with about 5% frequency is functionally almost completely deficient. Impaired activity associated with benzene toxicity and cancer chemotherapy induced leukemia. 

Hydroxylamine, IV-benzoyl-lV-phenyl-in gravimetry, 1, 532 liquid-liquid extraction, 1, 544 Hydroxylamine, A -cinnamoyl-A -phenyl-liquid-liquid extraction, 1,544 Hydroxylamine, Ar,A -di-(-butyl-metal complexes, 2, 798 Hydroxylamine, Ay/V-diethyl-metal complexes, 2,798 Hydroxylamine, AAmethyl-metal complexes, 2,798 Hydroxylamine, A -2-naphthol-A -nitroso-ammonium salt — see Ncocupferron Hydroxylamine, A -nilrosophenyl-ammonium salt — see Cupferron Hydroxylamine ligands, 2, 101 Hydroxylamine oxido reductase, 6, 727 Hydroxylases molybdenum, 6,658,662 Hydroxylation arenes... 

The three known crystal structures of molybdopterin-containing enzymes are from members of the first two families the aldehyde oxido-reductase from D. gigas (MOP) belongs to the xanthine oxidase family (199, 200), whereas the DMSO reductases from Rhodobacter (R.) cap-sulatus (201) and from/ , sphaeroides (202) and the formate dehydrogenase from E. coli (203) are all members of the second family of enzymes. There is a preliminary report of the X-ray structure for enzymes of the sulfite oxidase family (204). 

Oxido-reductase Dehydrogenases Cytochrome oxidase All phyla... 

S. Except for oxido-reductases, transferases, and hydrolases, most ligases (enzymes that catalyze bond formation) are entirely substrate specific. Thus, fumarate hydratase (or fumarase) reversibly and stereospecifically adds water to fumaric acid to produce (S)-( — )-malic acid only (8) (Figure 1), and another enzyme, mesaconase, adds water to mesaconic acid to form (+ )-citramalic acid (9) (Figure 2). Although no extensive studies are available, it appears that neither fumarase nor mesaconase will add water stereospecifically to any other a,(3-unsaturated acid. 

Davies, D. D., Teixeira, A., Kenworthy, P. The stereospecificity of nicotinamide-adenine dinucleotide-dependent oxido-reductases from plants. Biochem. J. 127, 335-343 (1972). 

Walpole CSJ, Wrigglesworth R (1987) Oxido-reductases - flavoenzymes. In Page MI, Williams A (eds) Enzyme mechanisms. The Royal Society of Chemistry, London,... 

The ferro-complex CD spectrum shows that reduction of the heme iron alters the heme environment. Redox-induced protein conformation changes could alter the S5unmetry in the heme pocket or produce two binding modes for the reduced complex whose asymmetries nearly cancel each other. Redox-linked conformational changes are especially interesting in view of recent findings of oxido-reductase activity associated with the heme-hemopexin-receptor interaction (89). 

The first sub-class of the oxido reductases is 1.1, and it comprises the dehydrogenases which act on primary or secondary alcohols or hemiacetals. They are mostly used for reduction of ketones and aldehydes. Two other categories are oxygenases and oxidases. The latter is not much used in biocatalysis. 

Mayer, B., John, M., Heinzel, B., Werner, E. R., Wachter, H., Schultz, G., and Bohme, E. (1991). Brain nitric oxide synthase is a biopterin- and flavin-containing multifunctional oxido-reductase. FEBS Lett. 288, 187-191. 

Ctrnacta V, Ault JG, Stejskal F, Keithly JS (2006) Localization of pyruvate NADP(+) oxido-reductase in sporozoites of Cryptosporidiumparvum. J Eukaryot Microbiol 53 225-231 Dederck PJ, Muller M (1987) Hydrogenosomal ATP AMP phosphotransferase of Trichomonas vaginalis. Comp Biochem Physiol 88 575-580 Docampo R, Moreno SN, Mason RP (1987) Free radical intermediates in the reaction of pyruvate ferredoxin oxidoreductase in Tritrichomonas foetus hydrogenosomes. J Biol Chem 262 12417-12420... 

Friedrich, T., VanHeek, P., Leif, H., Ohnishi, T., Forche, E., Kunze, B., Jansen, R., Trowitzsch-Kienast, W., Holfe, G., Reichenbach, H., and Weiss, H. Two binding sites of inhibitors in NADH ubiquinone oxidoreductase (complex I) relationship of one site with the ubiquinone oxido-reductase. Eur. J. Biochem., 219, 691, 1994. 

Thiosulfate cyanide sulfurtransferase symmetry in 78 TTiiouridine 234 Three-dimensional structures of aconitase 689 adenylate kinase 655 aldehyde oxido-reductase 891 D-amino acid oxidase 791 a-amylase, pancreatic 607 aspartate aminotransferase 57,135 catalytic intermediates 752 aspartate carbamyltransferase 348 aspartate chemoreceptor 562 bacteriophage P22 66 cadherin 408 calmodulin 317 carbonic acid anhydrase I 679 carboxypeptidase A 64 catalase 853 cholera toxin 333, 546 chymotrypsin 611 citrate synthase 702, 703 cutinase 134 cyclosporin 488 cytochrome c 847 cytochrome c peroxidase 849 dihydrofolate reductase 807 DNA 214, 223,228,229, 241 DNA complex... 

Complex III (ubiquinol-cytochrome c oxido-reductase or cytochrome bct complex). Mitochondrial complex III is a dimeric complex, each subunit of which contains 11 different subunits with a total molecular mass of 240 kDa per monomer.104-107 However, in many bacteria the complex consists of only three subunits, cytochrome b, cytochrome c , and the high potential ( 0.3 V) Rieske iron-sulfur protein, which is discussed in Chapter 16, Section A,7. These three proteins are present in all bc1 complexes. 

The reaction sequence catalyzed by TDPG oxido reductase is indicated below ... 

When this mechanism is compared with the one for TDPG-oxido reductase (Figure 2), several similarities are apparent. The axial hydrogen at carbon 4 is the initial point of attack which leads to the enzyme bound 4-ulose intermediate. Release of product from the enzyme occurs only after reoxidation of enzyme-NADH to enzyme-NAD+. A summary of available data to further substantiate our comparative study of TDPG-oxido reductase and UDP-galactose-4-epimerase is given in Table III. 

---