Keller P J, Le Van Q, Kim S U, Bown D H, Chen H C, Kohnle A, Bacher A, Floss H G
Department of Chemistry, Ohio State University, Columbus 43210.
Biochemistry. 1988 Feb 23;27(4):1117-20. doi: 10.1021/bi00404a006.
Feeding experiments with Ashbya gossypii followed by NMR analysis of the resulting riboflavin showed incorporation of deuterium from D-[2-2H]ribose at C-2' and from D-[1-2H]ribose in the pro-R position at C-1' of the ribityl side chain. The results rule out an Amadori rearrangement mechanism for the reduction of the ribosylamino to the ribitylamino linkage and point to formation of a Schiff base that is reduced stereospecifically opposite to the face from which the oxygen has departed. As prerequisite for the analysis, the 1H NMR signals for the pro-R and pro-S hydrogens at C-1' of 6,7-dimethyl-8-ribityllumazine and riboflavin and its tetraacetate were assigned with the aid of synthetic stereospecifically deuteriated samples.
