neosamine-c and 2-deoxystreptamine

Feeding experiments with D-[6,6-2H2]-, D-(6R)-[6-2H1]- and D-(6S)-[6-2H1]glucose in the fermentation of Streptomyces ribosidificus, followed by field desorption MS and 2H NMR analyses of the resulting labeled ribostamycin samples, clearly demonstrated that 1) both hydrogens of the C-6 hydroxymethyl group of D-glucose are stereospecifically incorporated into the C-2 position of 2-deoxystreptamine and 2) the pro S hydrogen of the C-6 position of D-glucose is stereospecifically removed during the elaboration of neosamine C in the biosynthesis of ribostamycin. A plausible mechanism of formation of the deoxy-scyllo-inosose, an early precursor to 2-deoxystreptamine, is suggested to be analogous to the dehydroquinate synthesis in the shikimate pathway and the conversion of the C-6 hydroxymethyl group of D-glucose into the aminomethyl group of neosamine C is likely to involve a dehydrogenation step to a formyl group.

Topics: Anti-Bacterial Agents; Chemical Phenomena; Chemistry; Fermentation; Glucosamine; Hexosamines; Isomerism; Magnetic Resonance Spectroscopy; Molecular Structure; Streptomyces