title: Influence of coenzyme structure on the transient chemical intermediate formed during horse-liver alcohol-dehydrogenase-catalyzed reduction of aromatic aldehydes.
abstract: The influence of coenzyme structure on the transient chemical intermediate formed in the reaction between the horse-liver alcohol dehydrogenase-NADH complex and an aromatic aldehyde such as 4-trans-(N,N-dimethylamino)cinnamaldehyde or 4-(N,N-dimethylamino)benzaldehyde was investigated by substituting various adenylic dinucleotides for NADH. Two classes of dinucleotide were studied. (a) Dinucleotides which, in the presence of horse-liver alcohol dehydrogenase and either 4-(N,N-dimethylamino)benzaldehyde or 4-trans-(N,N-dimethylamino)cinnamaldehyde, lead to a chromophore structurally analogous to the transient chemical intermediate formed with NADH under the same experimental conditions. This includes dinucleotides with a neutral 1,4-dihydropyridine ring, analogues of NADH and adducts of NAD+ (or analogues) with enolizable carbonyl compounds. (b) Dinucleotides which, under the same experimental conditions, do not form any new chromophores when mixed with horse-liver alcohol dehydrogenase and either 4-trans-(N,N-dimethylamino)cinnamaldehyde or 4-trans-(N,N-dimethylamino)benzaldehyde. This includes oxidized coenzyme analogues, NADPH and NADP+ adducts. Our data suggest that a neutral 1,4-dihydropyridine ring is crucial for the formation of the transient chemical intermediate. When the NAD+-sulphite complex, which has a 1,4-dihydronicotinamide structure and a positive charge at position 4 neutralized by sulphite ions, was substituted for NADH, the transient chemical intermediate chromophore was observed. The implications of this phenomenon are examined by assuming the existence of intermediate-activated forms of substrates and coenzymes during the horse-liver alcohol dehydrogenase catalytic reduction of aldehydes.
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism*; D001547:Benzaldehydes / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D002934:Cinnamates / Q000378:metabolism; D003067:Coenzymes / Q000378:metabolism*; D009243:NAD / Q000031:analogs & derivatives / Q000378:metabolism; D009249:NADP / Q000031:analogs & derivatives / Q000378:metabolism; D013053:Spectrophotometry; D013329:Structure-Activity Relationship; D013447:Sulfites
chemical_list: D000447:Aldehydes; D001547:Benzaldehydes; D002934:Cinnamates; D003067:Coenzymes; D013447:Sulfites; D009243:NAD; D009249:NADP; C018523:4-dimethylaminocinnamaldehyde; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; C510241:p-dimethylaminobenzaldehyde