ANALYSIS OF THE BIOSYNTHETIC PROCESS OF CELLULOSE AND CURDLAN USING C-13-LABELED GLUCOSES

In order to elucidate the biosynthetic process of cellulose and curdla n, C-13-labeled polysaccharides were biosynthesized by Acetobacter xyl inum (IFO 13693) and Agrobacterium sp. (ATCC 31749), from culture medi a containing D-(1-C-13)glucose, D-(2-C-13)glucose, D-(4-C-13)glucose, or D-(6-C-13)glucose as the carbon source, and their structures were d etermined by C-13 NMR spectroscopy. The labeling was mainly found in t he original position, indicating direct polymerization of introduced g lucoses. In addition, the transfer of labeling from C-2 to C-1, C-3 an d C-5, from C-4 to C-1, C-2 and C-3, and from C-6 to C-1 was found in celluloses. In curdlan, the transfer of labeling from C-1 to C-3, from C-2 to C-1, and C-3, from C-4 to C-1, C-2 and C-3, and from C-6 to C- 1 and C-3 was observed. From analysis of this labeling, the biosynthet ic process of cellulose and curdlan was explained as involving six rou tes. The percentages of each route via which cellulose or curdlan is b iosynthesized were estimated for upper (C-1 to C-3) and lower portions (C-4 to C-6) of glucosidic units in the polysaccharides. It is noted that very few polysaccharides are formed via the Embden-Meyerhof pathw ay. The lower half (C-4 to C-6) structure of introduced glucoses is we ll preserved in the polysaccharides.