Nicotinamide adenine dinucleotide dehydrogenase inhibitors

Cyclopropanone hydrate forms a stable thiohemiketal with the active-site thiol which is not oxidized by nicotinamide adenine dinucleotide (NAD). This hydrate has also been found to be a suicide inhibitor for horseradish peroxidase flavoenzyme alcohol oxidase and quinoprotein alcohol dehydrogenases ... 

A preliminary report by Obach and Van Vunakis (1990) claimed that cotinine could also be formed by a microsomal nicotinamide adenine dinucleotide (NAD) -dependent dehydrogenase (abbreviated MND). Inhibitor studies suggested that MND is not a typical aldehyde dehydrogenase. The presence of this activity in rabbit microsomes was confirmed in the authors laboratories (Flammang 1994). The rate of cotinine production from the -iminium by this route was found to be comparable to the rate of conversion of nicotine to the this enzyme might play in xenobiotic metabolism in general. It is expected that the substrate-structure dependence of MND will be quite different from that of cytosolic AO. 

Enzyme purification was the first application of bioaffinity chromatography [23] and remains an important use of this technique. In this type of separation, ligands, such as enzyme inhibitors, coenzymes, or cofactors, are used to purify and separate enzymes [25]. For instance, in 1968 and the first report of "modem" affinity chromatography, Cuatrecasas, Wilchek, and Anfinsen employed specific enzyme inhibitors to selectively isolate enzymes [1,4]. A more recent example was the use of a support containing flavin mononucleotides for the purification of flavin adenine dinucleotide synthetase [26]. Other examples have included the use of mono-, di-, and triphosphate nucleotides for the purification of kinases and the use of nicotinamide adenine dinucleotide for the isolation of dehydrogenases [26,27]. 

Enzyme-catalysed reactions are widely used for analytical purposes, for the determination of substrates (e.g. glucose oxidase for determination of glucose) and of inhibitors (such as pesticides, by their inhibition of cholinesterase) and activators. Although enzymes are very useful as analytical reagents, they are not classified individually in this Dictionary. However, enzymes themselves are extensively assayed by clinical chemists, biochemists, forensic scientists and food chemists, and the substrates used for such assays are carefully chosen to achieve optimum sensitivity, selectivity and reliability. Such substrates are listed in this Dictionary, as are the co-enzymes (co-factors) required by many redox enzymes, for example nicotinamide adenine dinucleotide (NAD /NADH) which is a co-enzyme for many dehydrogenases, e.g. 

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