ASSIGNMENT OF N-15-NMR RESONANCES OF VITAMIN-B12 ANALOGS BY 2D-[N-15,H-1] LONG-RANGE CORRELATION - FULLY [N-15]-LABELED CO-BETA-CYANO-5-HYDROXYBENZIMIDAZOYLCOBAMIDE (FACTOR-III) AND DERIVATIVES

The N-15-NMR spectra of vitamin B-12 analogues obtained in fully N-15-labelled form have been measured by direct and inverse (N-15,H-1) correlated spectroscopy. All resonances, except those of the NH2 groups, have been assigned to individual N-atoms. The influences on 6 (N) are analyzed and discussed which are caused by changing the beta-face ligand from CN to H2O or CH3 and by switching the alpha-face ligand from the base-on to the base-off state. An implication of the correct resonance assignment of biosynthetic pathways is demonstrated.