THE β-D -CONFIGURATION OF THE RIBOSYL NICOTINAMIDE PORTION OF DIPHOSPHOPYRIDINE NUCLEOTIDE
The configurations of the anomeric N-(tetra-O-acetyl-D-glucopyranosyl)-3-carboxamido-pyridium bromides were established by nuclear magnetic resonance (n.m.r.) spectroscopy. The β-D-anomer was found to undergo deacetylation without anomerization. This compound on oxidation with periodate has been shown (M. Viscontini and E. Hürzeler-Jucker. Helv. Chim. Acta, 39, 1620 (1956)) to yield a different product than did a synthetic N- (D-ribo-furanosyl)-3-carboxamidopyridinium chloride. Therefore, the anomeric configuration of the latter compound must be is α-D. Since its anomer was used (N. A. Hughes, G. W. Kenner, and A. Todd. J. Chem. Soc. 3733 (1957)) to synthesize diphosphopyridine nucleotide (DPN), the configuration of the anomeric center in this portion of the coenzyme must be β-D. Optical rotatory dispersion curves are reported for DPN, its component nucleotides, and the above-mentioned D-glucosides.