V%rio parahaemolyticus, a halophilic marine vibrio responsible for food poisoning, is now divided serologically into 12 (or 13) 0-serotypes'-4 based on differences in the serological specificities of its O-antigen [lipopolysaccharide (LPS)]. In our previous structural analysis5 of the sugar chain isolated from the LPS of I! parahaemolyticw serotype 012, it was shown that D-glucuronic acid (GlcA) is P-linked to O-2 of L-glycero-D-manno-heptose (L,D-Hep) which is linked to O-5 of 3-deoxy-D-manno-octulosonate (Kdo). Compositional sugar analysis of LPSs isolated from twelve 0-serotypes6.' revealed that uranic acid was distributed in the LPSs of all serotypes; however, two kinds of heptose, i.e., r_,D-Hep and D-glycero-D-manno-heptose (D,D-Hep), were detectable only in the LPS of serotype 02. These results suggest that the core region, in particular the inner core region, of 02 LPS is structurally different from that of 012 LPS. Acid hydrolysis of 02 LPS released two oligosaccharides, one consisting of uranic acid and r$-Hep and the other consisting of uranic acid, Lp-Hep, and D,D-Hep6. In the present study, we describe the isolation and identification of these oligosaccharides by means of GLC-MS and 'H and 13C NMR spectroscopy.
Disaccharide 2 and trisaccharide 5 were isolated from K parahaemolyticus 02 LPS (500 mg) after a two-step hydrolysis (acetic acid and CF,CO,H), methanolysis in hydrochloric acid, and peracetylation, HPLC purification afforded pure 2 (2.4 mg) and 5 (24.8 mg). GLC and GLC-MS of O-acetylated (S)-(+I-and (RI-(-)set-butyl glycosides* of the glucose (Glc) obtained from carboxyl-reduced 2 and 5 gave retention times (tR 17.25 and 17.52 min, respectively) and EI-mass spectra