Proton Nuclear Magnetic Resonance (' H-NMR) Signal Assignment of Vitamin B12 Based on Normal Two-Dimensional NMR and Feeding Experiments

Abstract

Proton nuclear magnetic resonance (1H-NMR) signal assignment of cyanocobalamin (vitamin B12) was achieved by the normal two-dimensional NMR method. 1H-1H correlation spectroscopy (COSY) of vitamin B12 showed correlation networks of dimethyl benzimidazole, ribose, isopropanolarnine and corrin ring proton peaks. 1H-1H nuclear Overhauser effect (NOE) spectroscopy (NOESY) allowed assignment of the benzimidazole protons. For assignment of methyl and methylene protons of the corrin ring, 1 H-13 C COSY measurements were made on 13 C-enriched vitamin B12, isolated after feeding experiments with [13 CH3]methionine [2-13 C]5-aminolevulinic acid (ALA), and [3-13 C]ALA. © 1989, The Pharmaceutical Society of Japan. All rights reserved.