The biosynthesis of l-rhamnose of plum-leaf polysaccharides

Abstract

The utilization of D-[1-C14]- and D-[6-C14] - glucose in the biosynthesis of L-rhamnose units of plum-leaf polysaccharides has been studied. After the precursors had been metabolized in the leaves, poly-saccharide fractions were prepared therefrom and the constituent L-rhamnose was isolated and purified. Both the specific activity and the distribution of C14 along the carbon chain of L-rhamnose from two poly-saccharide fractions from each experiment were determined. The results indicated a close affinity between L-rhamnose and pectin, and show that biosynthesis of the 6-deoxyhexose from D-glucose occurs in the main without scission or inversion of the carbon chain. A degradation scheme for L-rhamnose via L-rhamnitol was described which gives the labelling at-C-l, C-2+ C-3+C-4, C-5 and C-6 on a 0.3 millimole scale.