Ckrbolzydmre Research. 104 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA (1982) C4-C7 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands zyxwvutsrqponmlkjihgfedcb Preliminary communication 2,3-Diacetamido-2,3-dideoxy-D -mannuronic acid and its 2-imidazoline derivative: new acidic amino sugars from Pseudomonas aeruginosa 0: 3a,d lipopolysaccharide YURIY A_ KNIREL, EVGENIY V_ VINOGRADOV, ALEXANDER S. SHASHKOV, BORIS A. DMITRIEV, and NIKOLAY K. KOCHETKOV ?V. D. Zelinsk_v Institute of Organic Ckemistr_v. Academ,y of Sciences zyxwvutsrqponmlkjihgfedcbaZYXWVUT of the USSR.. Moscow fU_S.S_R) (Received January l&h, 1982; accepted for publication, March 3Ot!1, 1982) zyxwvutsrqponmlkjihgfedcbaZYXW 2,3-Diacetamido-2,3-dideoxy-D-glucuronic acid has been identified’ as a struc- tural component of the zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Ps_~eruginos~ 0:6 O-specific polysaccharide. We now report the identification of 2,3-diacetamido-2,3-dideoxy-D-mannuronic acid and 2,3-(l-acetyl-2- methyl-2-imidazolino-5,4)-2.3-dideoxy-D-mannuronic acid as constituents of the O- specific polysaccharide of A_ aemgzkosa, strain 170005 (serotype 0:3a,d, Lanyi classification). The acidic polysaccharide (MG~A OS; paper electrophoresis; pyridine acetate buffer, pH 4.5) was obtained by miId, acid degradation (1% CH,CO,HI 100°, 2 h) of the lipopolysaccharide isolated from dry bacterial cells by the Westphal procedure*. Hydrolysis (4~ HCl, 100°, 4 h) of the polysaccharide followed by conventional sugar analysis resulted in identification of 2-amino-2-deoxy-D-fucose hydrochloride, [~]g -l-60.5” (water), in 5% yieId as a singIe monosaccharide. The 13C-n.m.r. spectrum of the polysaccharide contained signals for three anomeric carbons (100.8, 99.8, and 98.3 p.p_m.), five carbons carrying nitrogen (57.6, 52.8, 52.4, 51.0, and 48.7 p.p.m_), one C-methyl group of a 6-deoxyhexose (16.4 p-p-m_), acetamido methyl groups at 23.1 p-p-m., and carbonyl groups in the region 174-176 p.p_m., as well as two sisals at 19.7 and 167.1 p-p-m. subsequently assigned to C-methyi and C-2, respectively, of a 2-imidazoline derivative (see below). Signals for hydroxymethyl groups were absent from the spectrurr. Therefore, it is proposed that the trisaccharide repeating-unit of the polysaccharide com- prises 2-acetamido-2-deoxy-D-fucose and, probably, two diaminodideoxyuronic acid derivatives. So!voIysis3 of the po!ysaccharide with hydrogen fluoride (25” , 3 h) gave the acidic trisaccharide I, f?&&4 0.5, which was isolated by gel filtration on Sephadex G-15 in almost quantitative yield. The ‘3C-n.m.r. spectrum of 1 showed that the solvolysis had cleaved selectively the N-acetylfucosaminidic linkages. Thus, 1 was the chemical re- peating-unit of the polysaccharide. Treatment of 1, in sequence, with borohydride, per- 000~qj21~/82/0000-0000/$02.75 0 1982 Elsevier Scienti5c Publishing Company