Semino C E, Dankert M A
Instituto de Investigaciones Bioquímicas Fundación Campomar, Facultad de Ciencias Exactas y Naturales and Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
J Gen Microbiol. 1993 Nov;139(11):2745-56. doi: 10.1099/00221287-139-11-2745.
Acetobacter xylinum strain NRRL B42 and its derivative RCGr1 produce a complex exopolysaccharide, acetan, containing glucose, mannose, glucuronic acid and rhamnose in a 4:1:1:1 molar ratio. The in vitro synthesis of acetan, employing electroporated cells as the enzyme system and the respective 14C-labelled sugar nucleotide precursors, is described. The synthesis of the prenyl-linked heptasaccharide repeat unit, already observed in EDTA-treated cells, was confirmed, as well as the formation of other saccharides not related to acetan biosynthesis, including a high molecular mass glucan. The acetan formed was characterized by gel filtration, specific radioactive labelling with each precursor and permethylation analysis. It was also shown that acetan contains acetyl residues and that using [14C]acetyl CoA as donor, radioactivity was detected both at the polysaccharide and at the prenyl-linked oligosaccharide stage.
木醋杆菌NRRL B42菌株及其衍生物RCGr1产生一种复杂的胞外多糖——乙酰聚糖，其葡萄糖、甘露糖、葡萄糖醛酸和鼠李糖的摩尔比为4:1:1:1。本文描述了以电穿孔细胞作为酶系统，并使用各自的14C标记糖核苷酸前体在体外合成乙酰聚糖的过程。已在经乙二胺四乙酸（EDTA）处理的细胞中观察到的异戊烯基连接的七糖重复单元的合成得到了证实，同时也证实了与乙酰聚糖生物合成无关的其他糖类的形成，包括一种高分子量葡聚糖。通过凝胶过滤、用每种前体进行特异性放射性标记以及全甲基化分析对形成的乙酰聚糖进行了表征。研究还表明，乙酰聚糖含有乙酰基残基，并且以[14C]乙酰辅酶A作为供体时，在多糖和异戊烯基连接的寡糖阶段均检测到了放射性。
