Abstract
Showdomycin, 2-β-D-ribofuranosylmaleimide, inhibited the incorporation of amino acids and purine and pyrimidine bases into macromolecules in E. coli K-12 cells at low concentrations. The inhibitory action of showdomycin could be reversed by the addition of a nucleoside or a sulfhydryl compound. In marked contrast to common nucleosides, the pseudouridine showed no such effect. This may indicate that the N-glycosyl linkage in the nucleoside is a structural requirement for its reversing activity on the inhibitory action of showdomycin.
N-Ethylmaleimide, which has structural similarity to showdomycin, inhibited the in-corporation of amino acids and purine and pyrimidine bases as well as showdomycin. The inhibitory action of N-ethylmaleimide, however, was not reversed by the addition of a nucleoside. This may indicate that there may be difference in the mechanism of the inhibitory action between N-ethylmaleimide and showdomycin.
