Biosynthesis of Xyloglucan in Suspension-Cultured Soybean Cells. Synthesis of Xyloglucan from UDP-Glucose and UDP-Xylose in the Cell-Free System

摘要

When UDP-[14C]glucose or UDP-[14C]xylose was incubated with a particulate fraction from soybean cells, radioactive polymers were synthesized. On digestion withAspergillus oryzaeenzymes, these polymers gave14C-monosaccharides and a14C-disaccharide with chromatographic and electrophoretic mobilities indistinguishable from those of authentic isoprimeverose (6-O-α-D-xylopyranosyl-D-glucopyranose). The disaccharide consisted of xylose and glucose, and the latter was located at the reducing end. Evidence that the disaccharide is isoprimeverose was provided by methylation analysis. Hydrolysis of the methylated disaccharide yielded 2,3,4-tri-O-methyl-D-xylose and 2,3,4-tri-O-methyl-D-glucose. Thus, incorporation of radioactivity into isoprimeverose, the smallest structural unit of xyloglucan, suggests that xyloglucan is synthesized in vitro from UDP-glucose and UDP-xylose