STRUCTURAL-ANALYSIS OF THE O-ANTIGENIC POLYSACCHARIDE FROM THE ENTEROPATHOGENIC ESCHERICHIA-COLI O125

The structure of the polysaccharide part of the lipopolysaccharide obt ained from the enteropathogenic Escherichia coli O125 has been investi gated. Methylation analysis, H-1-NMR spectroscopy and C-13-NMR spectro scopy revealed that the polysaccharide is composed of repeating hexasa ccharide units. Smith degradation of the native O-polysaccharide resul ted in a polysaccharide with four sugar residues in the repeating unit . Information on the sequence of the native O-polysaccharide and the S mith-degraded product was obtained by two-dimensional-NMR techniques, namely heteronuclear-multiple-bond-connectivity and NOESY experiments. The structure of the repeating unit of the O-polysaccharide of E. col i strain O125, which has two adjacent branch-point residues, is [GRAPH ICS] n acyl-CoA thioesterases. In addition, an enzyme that hydrolyzed acetoacetyl-CoA was partially purified; it was induced about 3.5-fold by di(2-ethylhexyl)phthalate treatment. In conclusion, these results d emonstrate that rat liver mitochondria contain several enzymes capable or hydrolyzing short-chain acyl-CoA, indicating that regulation of th e metabolism of short-chain acyl-CoAs and formation of ketone bodies, could be complex.