. Can. J. Chem. 69, 1273Chem. 69, (1991.AK1401 is a mutant of Pseudomonas aeruginosa strain PA01 (serotype 05) that does not express 0-antigen, but does express "A-band" lipopolysaccharide (LPS). The polysaccharide portion of the A-band LPS (A-PS) from AK1401 was found to consist mainly of D-rhamnose, with smaller amounts of 3-0-methylrhamnose, ribose, mannose, glucose, and a 3-0-methylhexose. 'H nuclear magnetic resonance spectra of the intact A-PS indicated that the main structural feature was a repeating trisaccharide of a-D-rhamnose having the following structure:The 'H NMR spectrum of the repeating unit was completely assigned through the use of 2D shift-correlated and relayed coherence transfer NMR spectroscopy. ' The linkage positions and sequence of residues were found by nuclear Overhauser enhancement difference spectroscopy. Le AK1401 est une espkce mutante du Pselcdomonas aeruginosa de la lignte PA01 (strotype 0 5 ) qui n'exprime pas de 0-antigkne, mais qui exprime un lipopolysaccharide (LPS) de abande-A),. On a trouvC que la portion polysaccharide du LPS de bande-A du AK1401 est principalement formCe de D-rhamnose, avec des quantitCs plus faibles de 3-0-mtthylrhamnose, de ribose, de mannose, de glucose et d'un 3-0-mtthylhexose. Les spectres de rtsonance magnCtique nucltaire du 'H du PS-A indiquent que la caracttristique structurale principale est un motif trisaccharide de a-D-rhamnose, de structure : Faisant appel2 la RMN en 2D avec corrtlation des dtplacernents et transfert de cohCrence par relais, on a fait une attribution complkte du spectre RMN du 'H du motif. On a dttermint les positions de liaison et la stquence des rtsidus par l'effet Overhauser nuclCaire differentiel.

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, 1376 (1994). Hepta-O-acetyl-O-a-~-Rhap-(1+3)-O-a-~-Rhap-(l+2)-glycerol