An enzymatically active artificial redox coenzyme based on a synthetic dye template
1997; Elsevier BV; Volume: 20; Issue: 1 Linguagem: Inglês
10.1016/s0141-0229(96)00074-9
ISSN1879-0909
AutoresSheila B. McLoughlin, Christopher R. Lowe,
Tópico(s)Biochemical Acid Research Studies
ResumoAn analogue of the reactive textile dye, Cibacron Blue F3G-A, has been modified with nicotinamide to produce an artificial redox coenzyme, Blue N-3, whose properties reflect the dual presence of a blue anthraquinone chromophore and an n-substituted nicotinamide ring. The reduced coenzyme generated concomitantly with the oxidation of alcohols by horse liver alcohol dehydrogenase (HLADH) displayed difference absorbance (Δλmax 333 nm) and 1H-NMR spectra consistent with the presence of a 1,4-dihydro-nicotinamide ring. The artificial coenzyme mediated the HLADH-catalyzed oxidation of primary aliphatic and cyclic alcohols with pentan-1-ol being the best cosubstrate of those tested and exhibiting a turnover of 8.5% of that shown by NAD+ at pH 9.0 and 25°C. The apparent Michaelis constant (Km for Blue N-3 (38 μM) with ethanol as cosubstrate was similar to that of NAD+ (10 μM) determined with HLADH and the reaction followed a similar ordered mechanism. The relative catalytic efficiency [kcatKm(M−1s−1)] of Blue N-3 was 0.4% of that shown by NAD+ under these conditions. The artificial coenzyme also displayed activity with human liver β1β1 alcohol dehydrogenase and sheep liver sorbitol dehydrogenase, two members of the same long-chain/polyol dehydrogenase family of enzymes. The artificial coenzyme appears to bind to these enzymes, inducing a conformational change and producing a catalytically competent complex in a maner similar to the natural coenzyme.
Referência(s)