The conversion of D-glucose to 5-keto-6-deoxy-D-arabohexose.

Hygromycin A is interesting from the standpoint of the previously undescribed sugar it contains, 5-keto-6-deoxy-n-arabohexose (2,3). The pathway of biosynthesis of this compound is unknown. In this study, Streptomyces hygroscopicus was grown in the presence of specifically labeled glucose, and the distribution of radioactivity in the 5-keto-6-deoxy-n-arabohexose of hygromycin A was determined. Since it was not possible to isolate the sugar as such, it was necessary to reduce the ketone group to an alcohol. The sugar was then isolated as the L-fucose diethylmercaptal derivative. The results of these experiments indicate that the n-glucose carbon chain is converted to that of 5-keto-6-deoxy-n-arabohexose without skeletal rearrangement, since little or no randomization of the isotope occurred.