Nicotinamide adenine dinucleotide, reduced NADH

Fig. 9. Glucuionic acid pathway. NAD = nicotinamide-adenine dinucleotide NADH = reduced nicotinamide—adenine dinucleotide ...

In living organisms, aldehyde and ketone reductions are carried out by either of the coenzymes NADH (reduced nicotinamide adenine dinucleotide) or NADPH (reduced nicotinamide adenine dinucleotide phosphate). Although... 

NAAb Natural autoantibody NAb Natural antibody NAC N-acetylcysteine NADH Reduced nicotinamide adenine dinucleotide NADP Nicotinamide adenine diphosphate... 

NADH reduced nicotinamide adenine dinucleotide SAM S-adenosyl methionine... 

NADH (reduced nicotinamide adenine dinucleotide) is utilized in biological reductions to deliver hydride to an aldehyde or ketone carbonyl group (see Box 7.6). A proton from water is used to complete the process, and the product is thus an alcohol. The reaction is catalysed by an enzyme called a dehydrogenase. The reverse reaction may also be catalysed by the enzyme, namely the oxidation of an alcohol to an aldehyde or ketone. It is this reverse reaction that provides the dehydrogenase nomenclature. 

A single enzyme is sometimes capable of many various oxidations. In the presence of NADH (reduced nicotinamide adenine dinucleotide), cyclohexanone oxygenase from Acinetobacter NCIB9871 converts aldehydes into acids, formates of alcohols, and alcohols ketones into esters (Baeyer-Villiger reaction), phenylboronic acids into phenols sulfides into optically active sulfoxides and selenides into selenoxides [1034], Horse liver alcohol dehydrogenase oxidizes primary alcohols to acids (esters) [1035] and secondary alcohols to ketones [1036]. Horseradish peroxidase accomplishes the dehydrogenative coupling [1037] and oxidation of phenols to quinones [1038]. Mushroom polyphenol oxidase hydroxylates phenols and oxidizes them to quinones [1039]. 

Figure 21 -8 Major glycolytic pathways of the erythrocyte. Substrates are in uppercase type, and enzymes are in parentheses. EMP, The Embden-Meyerhof pathway HMP hexose monophosphate pathway or pentose shunt RLC, the Rapoport-Luebering cycle ADP, adenosine diphosphate ATP, adenosine triphosphate NAD, nicotinamide-adenine dinudeotide NADH, reduced nicotinamide-adenine dinucleotide NADP, nicotinamide-adenine dinucleotide phosphate NADPH, reduced nicotinamide-adenine dinucleotide phosphate.The step from ribulose-5-phosphate, which is shown as being catalyzed by transketolase and transaldolase, is an abbreviation of this portion of the HMR...

ACP = acyl carrier protein ACPA D = ACPA desat-urase AlkB = octane 1-monooxygenase AOX = alternative oxidase DMQ hydroxylase = 5-demethoxyquinone hydroxylase EXAFS = extended X-ray absorption fine structure spectroscopy FMN = flavin mononucleotide FprA = flavoprotein A (flavo-diiron enzyme homologue) Hr = hemerythrin MCD = magnetic circular dichroism MME hydroxylase = Mg-protophorphyrin IX monomethyl ester hydroxylase MMO = methane monooxygenase MMOH = hydroxylase component of MMO NADH = reduced nicotinamide adenine dinucleotide PAPs = purple acid phosphatases PCET = proton-coupled electron transfer, PTOX = plastid terminal oxidase R2 = ribonucleotide reductase R2 subunit Rbr = rubrerythrin RFQ = rapid freeze-quench RNR = ribonucleotide reductase ROO = rubredoxin oxygen oxidoreductase XylM = xylene monooxygenase. 

Table 8.1 Summary of kinetic constants for the enzymes featured in Section 8.1 of Chapter 8. ALL the data are obtained from the enzyme database - BRENDA (http //www.brenda-enzymes.info/) except where indicated (a) vaLue of k n/Kn estimated assuming aLL substrate added in buffer is avaiLabLe to enzyme i.e., has not been sequestered as acetaL or ketaL derivatives, as appropriate) (b) kcat data from FieLds et aL, 2006 (c) /feat data from rat source (d) kinetic data from Masaki et ai, 2001 (e) /Ccat data from Day and Shaw, 1992 (f) kinetic data from bovine source (g) kinetic data from human source (h) aLL kinetic data from Wright et ai, 2006. Abbreviations GAP 3-gLyceraLdehyde 3-phosphate DHAP dihydroxyacetone phosphate OAA oxaLoacetate NADH reduced nicotinamide adenine dinucLeotide chloramp chLoramphenicoL thio-ACh thio acetyLchoLine. Roman numeraL denote compounds iLLustrated in the set of structures accompanying this tabLe. 

A and B Hbd, 3-hydroxybutyryl-CoA dehydrogenase NADH, reduced nicotinamide adenine dinucleotide (reduced form) Pta, phosphotransacetylase Ptb, phosphotrans-butyrylase ThI, thiolase. The single reactions do not represent stoichiometric fermentation balances. 

BODIPY Refe toafoixiilyofdyesbasedon 1,3 5.7,8- NADH Reduced nicotinamide adenine dinucleotide... 

Nature makes use of NADH (reduced nicotinamide adenine dinucleotide) as a cofactor for enantioselective biochemical hydrogenations, which are typical hydride-transfer reactions. Dihydropyridines and benzimidazolines derivatives are active hydride donors due to the presence of the nitrogen atom and the ability of the molecule to undergo aromatisation. Organocatalytic enantioselective reductions carried out using hydride donors has been studied, and effective reductions have been achieved with imidazoli-dinone organocatalysts, both with a,p unsaturated aldehydes and ketones. Generally, a stoichiometric quantity of reductant (Hantzsch ester 4) is required for these transformations (Scheme 18.5). 

Scheme 11.27. A representation of the reduction of pyruvate to S-lactate (L-lactate) by action of the enzyme lactate dehydrogenase and the cofactor NADH (reduced nicotinamide adenine dinucleotide, which is oxidized to NAD [nicotinamide adenine dinncleotide]) in the process.

Using a CNT-coated graphite electrode, Wang et al. have demonstrated a good voltammetric resolution for DA and AA with an anodic potential difference of 270 mV in a pH 5.0 phosphate buffer, which indicates a high selectivity for DA over AA. The observed difference in electrocatalysis toward DA and AA was attributed to a three-dimensional (3D) porous interfacial layer associated with the CNT-modified electrode. The CNT-modified electrodes were also found to exhibit a strong and stable electrocatalytic response to NADH (reduced nicotinamide adenine dinucleotide) with a... 

In biological systems, the redox coenzymes NADH (reduced nicotinamide adenine dinucleotide phosphate) and NADPH, the 2 -phosphoric acid derivative of NADH, belong to the most prominent and important examples of... 

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