STRUCTURAL ELUCIDATION OF THE O-ANTIGENIC POLYSACCHARIDE FROM ESCHERICHIA-COLI O44/H18

The O-antigen polysaccharide of the lipopolysaccharide from the enteroaggregative Escherichia coli O44:H18 has been investigated. Sugar and methylation analysis, H-1- and C-13-NMR spectroscopy revealed that the polysaccharide is composed of pentasaccharide repeating units. The sequence of sugar residues was determined by use of two-dimensional nuclear Overhauser effect spectroscopy and heteronuclear multiple bond correlation experiments. The structure of the repeating unit of the O-antigen from Escherichia coli 044:H18 is as follows. [GRAPHICS] n of bilirubin-IX alpha to bilirubin-IX beta in the bile and the small intestinal contents of fetuses. As development proceeded from mid-gestation to near term, the isomeric composition dramatically changed, with a decrease in the IX beta isomer and a subsequent increment of the IX alpha isomer. In contrast, the IX delta isomer changes little. Recently, we identified four forms of biliverdin reductase including two biliverdin-IX alpha: reductases and two biliverdin-IX beta reductases in human liver cytosolic fractions [Yamaguchi, T., Komoda, Y. & Nakajima, H. (1994) J. Biol. Chem. 269, 24343-24348]. The proportion of the total activity of biliverdin-IX beta reductases to that of biliverdin-IX alpha reductases was considerably higher in the fetal, than in the adult liver.