Radziejewska-Lebrecht J, Shashkov A S, Stroobant V, Wartenberg K, Warth C, Mayer H
Instytut Mikrobiologii, Uniwersytet Lódzki, Poland.
Eur J Biochem. 1994 Apr 1;221(1):343-51. doi: 10.1111/j.1432-1033.1994.tb18746.x.
The inner-core region of the lipopolysaccharide of an UDPGalNAc-4-epimerase-deficient mutant of Yersinia enterocolitica 0:3, designated as Ye75R, was investigated using methylation analysis, 1D-13C-NMR and 2D-13C-NMR and 1H-NMR, as well as 31P-NMR, fast-atom-bombardment mass spectrometry (FAB MS) and FAB MS/MS in positive and negative modes. The isolated core heptasaccharide (OS) was composed of 2 units D-glucose, 3 units LD-heptose and 1 unit each of DD-heptose and 3-deoxy-D-manno-octulosonic acid. Methylation analysis indicated that OS was highly branched with terminal location of the two glucoses and the DD-heptose unit, which was partially (to about 40%) phosphorylated at C7. These combined studies allowed us to formulate the structure of the inner core region as shown in Scheme 1. The substitution of the 7-position of the terminally linked DD-heptose unit by phosphate could be recognized by MS characterization of permethylated DD-heptose-7-phosphate (alditol acetate) and the extent of the substitution by the ratio of the two well separated 1H signals of DD-heptose in 500-MHz 1H-NMR. Negative FAB MS of OS also indicated the presence of smaller amounts of two hexasaccharides, differing from OS in lacking either one terminal unit of D-glucose or of the terminal DD-heptose, and additionally of a pentasaccharide lacking two heptosyl units, namely the terminal DD-heptose and and the subterminal LD-heptose. The presence of the smaller oligosaccharides in the OS fraction was also recognized by the methylation analysis.
对小肠结肠炎耶尔森菌0:3的UDPGalNAc - 4 - 表异构酶缺陷型突变体（命名为Ye75R）的脂多糖内核区域进行了研究，采用了甲基化分析、一维碳核磁共振（1D - 13C - NMR）、二维碳核磁共振（2D - 13C - NMR）、氢核磁共振（1H - NMR）以及磷核磁共振（31P - NMR）、快原子轰击质谱（FAB MS）和正负模式下的FAB MS/MS。分离得到的核心庚糖（OS）由2个D - 葡萄糖单元、3个L - D - 庚糖单元以及各1个D - D - 庚糖和3 - 脱氧 - D - 甘露糖辛酮酸单元组成。甲基化分析表明，OS高度分支，两个葡萄糖和D - D - 庚糖单元位于末端，D - D - 庚糖单元在C7处部分（约40%）磷酸化。这些综合研究使我们能够确定内核区域的结构，如图1所示。通过对全甲基化的D - D - 庚糖 - 7 - 磷酸（乙酰糖醇乙酸酯）的质谱表征以及500兆赫氢核磁共振中D - D - 庚糖两个分离良好的氢信号的比例，可以识别末端连接的D - D - 庚糖单元7位被磷酸取代的情况。OS的负离子FAB MS还表明存在少量的两种己糖，它们与OS的不同之处在于分别缺少一个末端D - 葡萄糖单元或末端D - D - 庚糖单元，此外还有一种缺少两个庚糖基单元（即末端D - D - 庚糖和次末端L - D - 庚糖）的戊糖。OS组分中较小寡糖的存在也通过甲基化分析得以确认。
