The receptor of coliphage omega8 is the O-specific mannan of Escherichia coli O8 in which the trisaccharide alpha-mannosyl-1,2-alpha-mannosyl-1,2-mannose is joined through alpha-mannosyl-1,3-linkages. Coliphage omega8 produces an endo-alpha-1,3-mannosidase which destroys the receptor, liberating a series of oligosaccharides (repeating trisaccharide and multiples). The enzyme is an integral part of the phage particles and also occurs in a free form in the lysates. Phage particles hydrolyze alpha-1,3-mannosyl linkages in the lipopolysaccharide, the polysaccharide (mannan) moiety, and higher oligosaccharides with an efficiency decreasing in this order. No transmannosylation could be detected. Phage particles also degrade the receptor mannan on whole bacteria, as determined with 14C-labeled E. coli O8. The values of Km and Vmax were determined with omega8 particles and free enzymes using native lipopolysaccharide and its triethylammonium salt. The latter, which was obtained after electrodialysis, has a micellar weight of 2.5 X 10(5), whereas the native lipopolysaccharide forms supermicelles with micellar weights of several millions. With coliphage omega8 as enzyme and supermicellar lipopolysaccharide as substrate Km=5 X 10(-8) M was obtained. This, together with the fact that omega8 attaches irreversibly to E. coli O8, was used in proposing a hypothesis for the possible role of the enzyme in the first steps of infection with coliphage omega8.
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机译：大肠杆菌噬菌体omega8的受体是大肠杆菌O8的O特异甘露聚糖，其中三糖α-甘露糖基1,2-α-甘露糖基-1,2-甘露糖通过α-甘露糖基1,3-键连接。鹅肠杆菌omega8产生内α-1,3-甘露糖苷酶，破坏该受体，释放出一系列寡糖（重复三糖和倍数）。酶是噬菌体颗粒的组成部分，并且也以游离形式存在于裂解物中。噬菌体颗粒水解脂多糖，多糖（甘露聚糖）部分和高级寡糖中的α-1,3-甘露糖基键，其效率以此顺序降低。没有检测到反式甘露糖基化。噬菌体颗粒还会降解整个细菌的受体甘露聚糖，如14C标记的大肠杆菌O8所测定。使用天然脂多糖及其三乙基铵盐，使用omega8颗粒和游离酶测定Km和Vmax值。后者是在电渗析后获得的，其胶束重量为2.5 X 10（5），而天然脂多糖形成胶束重量为数百万的超胶束。以大肠杆菌噬菌体omega8为酶，超胶束脂多糖为底物，得到Km = 5 X 10（-8）M。这与omega8不可逆地附着在大肠杆菌O8上的事实一起，被用来提出一种假设，即酶在感染噬菌体omega8的第一步中可能发挥的作用。
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