On the nuclear magnetic resonance spectrum of reduced nicotinamide adenine dinucleotide

✍ Scribed by Donald P. Hollis

• Publisher: John Wiley and Sons
• Year: 1969
• Tongue: English
• Weight: 366 KB
• Volume: 1
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1270010404

✦ Synopsis

The two C-4 protons of reduced nicotinamide adenine dinucleotide (NADH) produce an AB NMR spectrum at 100 MHz as well as at 220 MHz. This observation allows an upper limit of 50 sec-l to be placed on the mean rate of interconversion of the two folded forms of NADH invoked to account for the magnetic non-equivalence of the C-4 protons. The interpretation of nonequivalence of the C-4 protons in terms of the various equilibria among folded and unfolded forms of NADH and its possible significance in the mechanism of action of dehydrogenase enzymes is discussed. It is suggested that one folded form of NADH is strongly favored thermodynamically over the other and that the resulting magnetic non-equivalence of the C-4 protons is of doubtful significance in explaining the stereospecificity of dehydrogenase enzymes toward the nicotinamide ring.

* Although Jardetzky and Wade-Jardetzky report 20 to 40% of the NAD+ molecules are in the folded form, this value seems to have resulted from an error in calculating the equilibrium constant. Thus, in Table 11 of their paper AF" for folding is given as -0.68 Kcal/mole while the equilibrium constant for the folding reaction is given as 0.36. The correct value is 3.5.