Structure of the O-Specific Polysaccharide of the Bacterium Proteus mirabilis O13 Containing a Novel Component: an Amide of D-Galacturonic Acid with N^epsilon-(1-Carboxyethyl)lysine

A. S. Shashkov,¹ F. V. Toukach,¹ S. N. Senchenkova,¹ A. Ziolkowski,² N. A. Paramonov,¹ W. Kaca,² Yu. A. Knirel,^1,3 and N. K. Kochetkov¹

¹Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Leninskii pr. 47, Moscow, 117913 Russia; fax: (7-095) 135-53-28; E-mail: knirel@ioc.ac.ru

²Center of Microbiology and Virology, Polish Academy of Sciences, ul. Lodowa 106, 93-232 Lodz, Poland; fax: (48-42) 49-16-33.

³To whom correspondence should be addressed.

Submitted October 25, 1996; revision submitted January 20, 1997.

---

An acidic O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of the bacterium Proteus mirabilis O13 and found to contain D-galactose, 2-acetamido-2-deoxy-D-glucose, and N^epsilon-(1-carboxyethyl)-N^alpha-(D-galacturonoyl)lysine. On the basis of full acid hydrolysis and ¹H- and ¹³C-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY), H-detected heteronuclear ¹H,¹³C multi-quantum coherence (HMQC), and rotating-frame nuclear Overhauser effect spectroscopy (ROESY), the following structure of the branched trisaccharide repeating unit of the polysaccharide was established (see full article for figure).

---

KEY WORDS: O-antigen, bacterial polysaccharide, D-galacturonic acid, amide, N^epsilon-(1-carboxyethyl)lysine, structure, NMR spectroscopy, Proteus mirabilis.

---