Structure of the O-specific polysaccharide of the bacterium Proteus mirabilis O10 containing L-altruronic acid, a new component of O-antigens

An acidic O-specific polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of the bacterium Proteus mirabilis O10 and studied by full acid hydrolysis, carboxyl reduction, and H-1- and C-13-NMR spectroscopy, including two-dimensional correlation spectroscopy (COSY4), H-detected heteronuclear H-1, C-13 multi-quantum coherence (HMQC), and rotating-frame nuclear Overhauser effect spectroscopy (ROESY). It was found that the polysaccharide contains 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-galactose, D-galacturonic acid, and L-altruronic acid, and the following structure of the branched tetrasaccharide repealing unit of the polysaccharide was established: [GRAPHICS] t azide-facilitated decay of the M intermediate and shift the linear part of the dose-response curve of the effect of the azide concentration on the intermediate M decay rate to higher azide concentrations. The efficiency of azide as an accelerator of the M intermediate decay in these two populations decreases 11- and 140-fold in the presence of glutaraldehyde and 200- and 1600-fold in the presence of LuCl3. Glycerol and sucrose induce deceleration of the M intermediate decay in the wild-type bacteriorhodopsin and in the D96N mutant in the presence of azide, A scheme for the photocycle is suggested that assumes an equilibrium of two M intermediate forms differing in permeability for azide and, probably, for water molecules.