Biosynthesis of 13C-labeled branched polysaccharides by pestalotiopsis from 13C-labeled glucoses and the mechanism of formation

Biosynthesis of branched glucan by Pestalotiopsis from media containing D-(1-C-13)glucose, D-(2-C-13)glucose, D-(4-C-13)glucose, D-(6-C-13)glucose or a mixture of D-(1-C-13)glucose and D-(2-C-13)glucose was carried out to elucidate biosynthetic mechanism of branched polysaccharides. C-13 NMR spectra of the labeled polysaccharides were determined and assigned. Analysis of C-13 NMR spectra of glucitol acetates obtained from hydrolysates of the labeled branched polysaccharides indicated that transfer of labeling from C-1 to C-3 and C-6 carbons, from C-2 to C-1, C-3 and C-5 carbons, and from C-6 to C-1 carbon. From the results the percentages of routes via which the polysaccharide is biosynthesized are estimated. They show that the biosynthesis of the polysaccharide via the Embden-Meyerhof pathway and that from lipids and proteins are more active, and the pentose cycle is less active, than in the biosynthesis of cellulose and curdlan. As for the results, labeling at C-6 carbon in the branched polysaccharide cultured from D-(6-C-13)glucose was low, compared to that of cellulose and curdlan. (C) 1998 Elsevier Science Ltd. All rights reserved.