Relationship of the structure and biological activity of the natural homologues of tunicamycin.

The antibiotic tunicamycin was separated into 16 different components using reversed-phase high performance liquid chromatography. The effect of the eight major tunicamycin homologues on protein glycosylation and protein biosynthesis was examined. All homologues tested inhibited lipid-mediated protein glycosylation in chick or mouse fibroblasts. These homologues also inhibited the transfer of N-acetylglucosamine-1-phosphate from UDP-N-acetylglucosamine to dolichyl phosphate in chick liver microsome preparations, whereas the transfer of mannose from GDP-mannose to the lipid acceptor was hardly affected. The inhibition of protein glycosylation in fibroblasts or in microsomal preparations was concentration-dependent and maximum inhibition occurred at different concentrations for different homologues. The eight homologues differed in their ability to cause inhibition of protein synthesis.