Luminescence studies on the conformational behavior of horse-liver alcohol dehydrogenase

The luminescence quenching and conformational behaviour of alcohol dehydrogenase from horse liver upon substrate binding has been studied. It was shown that the binding of NADH and NAD+ to the enzyme resulted in the quenching of Trp-314 luminescence, whereas the luminescence of Trp-15 was not quenched. In this case nonradiating energy transfer from Trp-314 to NADH was observed. An essential energy transfer from Trp-15 to NADH and between the two Trp-314 residues of both subunits of the enzyme was not revealed. The quenching of the enzyme luminescence upon NAD+ binding was caused mainly, by NAD+ reduction to NADH. It was assumed that the release of the proton upon NAD+ binding occurred due to the reduction. Binding of ethanol, ADP or adenosine did not result in essential conformational changes of the enzyme.