| Abstract: | The antibiotic, tsushimycin, inhibits the formation of dolichyl phosphate mannose, dolichyl phosphate glucose and dolichyl pyrophosphate N-acetylglucosamine in the particulate enzyme preparation from pig aorta. Although this antibiotic also inhibits the incorporation of mannose and glucose into lipid-linked oligosaccharides, these reactions are less sensitive to antibiotic than those involved in the synthesis of lipid-linked monosaccharides. In the presence of tsushimycin, most of the mannose incorporated into lipid-linked oligosaccharides is into one oligosaccharide that has the properties of the heptasaccharide Man5GlcNAc2, whereas in the absence of antibiotic most of the mannose is in larger-sized oligosaccharides. On the other hand, the glucose-labelled lipid-linked oligosaccharides appear to be similar in size in the presence or absence of antibiotic. Tsushimycin also inhibits the formation of lipid-linked monosaccharides by the solubilized enzyme preparation of aorta. Various concentrations of dolichyl phosphate or the detergent, Nonidet P40, had no effect on antibiotic inhibition. Some evidence indicates that tsushimycin binds to the particulate enzyme. |
