Studies of low molecular weight samples of glucuronans with various acetylation degree

Partially acetylated, high molecular weight glucuronans were produced by a Sinorhizobium meliloti mutant strain. Two native glucuronan samples with various degrees of acetylation were sonicated to obtain lower molecular weight samples and with low viscosity suitable for chemical modification and C-13 NMR experiments. The average degree of substitution ((DS) over bar) of the polymer was estimated by Fourier transform infrared (FTIR) and NMR. C-13 NMR spectra it-ere obtained and used to suggest a complete assignment of the signals. The nuclear Overhauser effect spectroscopy (NOESY) and heteronuclear multi-bond coherence (HMBC) experiments were used to elucidate connectivities between the various residues and deduce the linkage of these residues within the polysaccharide. (C) 2002 Wiley Periodicals, Inc.