Actinomycete metabolism. Incorporation of 14C-labelled compounds into streptomycin

Abstract

A 5% incorporation of C14D-glucase into streptomycin by Streptomyces griseus was obtained. This is 5 times the previous maximum (Karow et al 1952) and is due mainly to delaying the addition of labelled material until the organism has almost attained its maximum bulk (60 hours after inoculation). Chemical degradation showed that, within the limits of experimental error, the C14-D-glucase labels from uniformily-labelled glucose are distributed equally between the streptamine, streptose and N-methyl-L-glucosamine parts of the molecule. The carbons of the guanidine side chains contain much less radioactivity than the average of the other C atoms. The latter finding is consistent with the hypothesis that these carbons are incorporated only secondarily by way of CO2. Streptamine is not converted into streptomycin as efficiently as is glucose. C14-N-Methyl-L-glucosamine, added after the organism has grown for 60 hours, is incorporated into streptomycin in over 15% yield. Radioactivity is located largely in the corresponding part of the antibiotic molecule, but the L sugar also is converted into the streptidine moiety more efficiently than D-glucose. It is suggested that inversion of D-glucose to give L sugars proceeds by way of a hexitol-type intermediate.