The Peroxidatic Reaction Catalyzed by Horse Liver Alcohol Dehydrogenase. 3. Nuclear Magnetic Resonance Spectroscopic Study of NADX.

As previously reported [Favilla, R. & Cavatorta, P. (1975) FEBS Lett. 50, 324–329], the enzyme horse liver alcohol dehydrogenase catalyzes a reaction between NAD⁺ and H₂O₂. The final isolated product was then called NADX because of its unknown structure. In this paper the results of spectroscopic investigations on this compound are described. They indicate that only the nicotinamide moiety of the original NAD⁺ molecule was modified by the action of hydrogen peroxide. From the ¹H and ¹³C nuclear magnetic resonance spectra of NADX the following structure was deduced: adenosine(5′)diphospho(5)-β-D-ribose-NH-CH=C(CHO)-CONH₂. This structure is consistent with both ultraviolet and reactivity measurements performed on NADX. A tentative mechanism for the whole peroxidatic reaction pathway leading to NADX is finally proposed. [ABSTRACT FROM AUTHOR]