Oxidoreductases dehydrogenases

Oxidoreductases dehydrogenase, oxidase oxygenase, peroxidase oxidation or reduction... 

EC1 Oxidoreductases dehydrogenase, acceptor ECU Acting on the CH-CH (cholestenone 5a- Choline oxidase choline H202 Luminol 17... 

Oxidoreductases Dehydrogenases Reductases Oxidases Addition or subtraction of electrons... 

Enzymes are highly selective of the substrates with which they interact and in the reactions that they catalyze. This selective nature of enzymes collectively known as enzyme specificity can be best illustrated with oxidoreductases (dehydrogenases), which display substrate and bond specificities (e.g., acting on —CHOH—, versus —CHO versus —CH—CH— versus —CHNH2, and cis versus trans for unsaturated substrates), coenzyme specificity (e.g., NAD(H) versus NADP(H)), chiral stereospecificity (d- versus l- or R- versus S-stereoisomers), and prochiral stereospecificity (A versus B corresponding to proR- versus proS isomers and re face versus si face, respectively). The table lists some dehydrogenases and their coenzyme, substrate, product and stereospecificities (You, 1982) ... 

Other oxidoreductases (dehydrogenases) use electron acceptors other than oxygen, such as the cofactor NAD or NAD(P)". These cofactors maybe advan-t eously combined with electrochemical sensors, provided that the cofactor is externally supplied or immobilized and regenerated. More than 250 highly specific dehydrogenases are commercially available. Hydrolases are another class of readily available enzymes that can be combined with potentiometric sensors. Hydrolases catalyse the hydrolytic cleavage of C-O, C-N, C-C, and other bonds. Other biosensors can be fabricated from the new generation of hybrid and synthetic enzymes (17). 

Oxidoreductases Dehydrogenases Oxidases Reductases Introduction of double bond by removal of Ha Oxidation Reduction ... 

Aldehyde oxidoreductase (dehydrogenase) Formate dehydrogenase CO dehydrogenase (oxidoreductase)... 

Over 250 oxidoreductases (dehydrogenases) use the cosubstrate yS-nicotinamide adenine (phosphate) dinucleotide (NAD(P) ) to oxidize a substrate SHj with concomitant reduction of the cofactor to NAD(P)H. In the most cases the cofactor is bound simultaneously with the substrate in the active site of the enzyme, allowing transfer of a hydride ion from the substrate to NAD(P)-. ... 

Oxidoreductase dehydrogenase and flavoenzymes. Nicotinamide adenine dinucleotide (NAD+)/nicotinamide adenine dinucleotide phosphate (NADF) and flavin mononucleotide (FMN)/flavin adenine dinucleotide (FAD) are the two major types of redox coenzymes. 

Oxidoreductases (dehydrogenases or oxidases) catalyze the addition or the removal of hydrogen or electrons. Oxygenases bring about the incorporation of oxygen which originates from molecular oxygen. 

Oxidoreductases Dehydrogenases Oxidases Oxygenases Hydroxylases Peroxidases Oxidation and reduction reactions Addition or removal of H Two-electron transfer to Oj, forming H Oj Two-electron transfer to /cOj, forming H O Incorporate O into product Incorporate /cO into product as -OH and form H O Use as HjO as oxygen donor, forming H O... 

The two oxidoreductase systems most frequentiy used for preparation of chiral synthons include baker s yeast and horse hver alcohol dehydrogenase (HLAD). The use of baker s yeast has been recendy reviewed in great detail (6,163) and therefore will not be coveted here. The emphasis here is on dehydrogenase-catalyzed oxidation and reduction of alcohols, ketones, and keto acid, oxidations at unsaturated carbon, and Bayer-Vidiger oxidations. 

Acetoin dehydrogenase [from beef liver acetoin NAD oxidoreductase] [9028-49-3] Mr 76000, [EC 1.1.1.5]. Purified via the acetone cake then Ca-phosphate gel filtration (unabsorbed), lyophilised and then fractionated through a DEAE-22 cellulose column. The Km for diacetyl in 40pM and for... 

In order to broaden the field of biocatalysis in ionic liquids, other enzyme classes have also been screened. Of special interest are oxidoreductases for the enan-tioselective reduction of prochiral ketones [40]. Formate dehydrogenase from Candida boidinii was found to be stable and active in mixtures of [MMIM][MeS04] with buffer (Entry 12) [41]. So far, however, we have not been able to find an alcohol dehydrogenase that is active in the presence of ionic liquids in order to make use of another advantage of ionic liquids that they increase the solubility of hydrophobic compounds in aqueous systems. On addition of 40 % v/v of [MMIM][MeS04] to water, for example, the solubility of acetophenone is increased from 20 mmol to 200 mmol L ... 

Complex II (Succinate Dehydrogenase Succinate Ubiquinone Oxidoreductase)... 

Another pathway is the L-glycerol 3-phosphate shuttle (Figure 11). Cytosolic dihydroxyacetone phosphate is reduced by NADFl to s.n-glycerol 3-phosphate, catalyzed by s,n-glycerol 3-phosphate dehydrogenase, and this is then oxidized by s,n-glycerol 3-phosphate ubiquinone oxidoreductase to dihydroxyacetone phosphate, which is a flavoprotein on the outer surface of the inner membrane. By this route electrons enter the respiratory chain.from cytosolic NADH at the level of complex III. Less well defined is the possibility that cytosolic NADH is oxidized by cytochrome bs reductase in the outer mitochondrial membrane and that electrons are transferred via cytochrome b5 in the endoplasmic reticulum to the respiratory chain at the level of cytochrome c (Fischer et al., 1985). 

For reduction of acetylenic ketones, two oxidoreductases were used [25]. Lactobacillus brevis alcohol dehydrogenase (LBADH) gave the (R)-alcohols and Candida parapsilosis carbonyl reductase (CPCR) afforded the (S)-isomer, both in good yield and excellent enantioselectivity. By changing the steric demand of the substituents, the enantiomeric excess values can be adjusted and even the configurations of the products can be altered (Figure 8.34). 

Relkin N and Nelson T. Regulation and. properties of an NADP+ oxidoreductase which functions as a. y-hydroxybutyrate dehydrogenase. J Neurochem, 1983, 40, 1639. 

Oxidoreductases have a variety of functions in metabolism oxidases and dehydrogenases play major roles in respiration hydroperoxidases protect the body against damage by free radicals and oxygenases mediate the hydroxylation of drugs and steroids. 

Hetterich D, B Peschke, B Tshisuaka, F Lingens (1991) Microbial metabolism of quinoline and related compounds. X. The molybdopterin cofactors of quinoline oxidoreductases from Pseudomonas putida 86 and Rhodococcus sp. B1 and of xanthine dehydrogenase from Pseudomonas putida 86. Biol Chem Hoppe-Seyler 372 513-517. 

Axcell BC, PJ Geary (1973) The metabolism of benzene by bacteria. Purification and some properties of the ezyme cw-l,2-dihydroxycyclohexa-3,5-diene (nicotinamide adenine dinucleotide) oxidoreductase (ciT-benzene glycol dehydrogenase). Biochem J 136 927-934. 

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