Incorporation of UDP-( sup 14 C)glucose into xyloglucan by pea membranes
- McGill Univ., Montreal, Quebec (Canada)
The water-insoluble 1,4-{beta}-linked products formed from UDP-({sup 14}C)glucose by pea membranes were dissolved in hot dimethylsulfoxide/paraformaldehyde and fractionated on columns of controlled pore glass beads calibrated with dextran standards. The products eluted with a peak size close to 70 kilodaltons in dextran equivalents. Similar elution profiles were obtained for products formed in brief or extended incubations and at high or low substrate concentrations. Methylation analysis indicated that only a few ({sup 14}C)glucose units had been added to an endogenous acceptor to form this product. In the presence of UDP-xylose at concentrations equal to or less than UDP-({sup 14}C)glucose, incorporation from the latter was enhanced and the products elongated with time to a size range where the major components eluted between dextran 264 and 500 kilodaltons. Treatment with endo-1,4-{beta}-glucanase resulted in a mixture of oligosaccharides, including the xyloglucan subunit Glc{sub 4}Xyl{sub 3}, which were hydrolyzed further by mixed glycosidases to labeled glucose and isoprimeverose (xylosyl-1,6-{alpha}-D-glucose). In pulse-chase experiments, low molecular weight product formed from UDP-({sup 14}C)glucose alone was clearly a precursor for high molecular weight products formed subsequently in the presence of both UDP-glucose and UDP-xylose. It is concluded that the 1,4-{beta}-transglucosylation activity detected in these tests was due to an enzyme that is required for biosynthesis of the backbone of xyloglucan.
- OSTI ID:
- 5857944
- Journal Information:
- Plant Physiology; (USA), Vol. 91:1; ISSN 0032-0889
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GLUCOSE
METABOLISM
BIOSYNTHESIS
CARBON 14 COMPOUNDS
ENZYME ACTIVITY
IN VITRO
PISUM
TRACER TECHNIQUES
ALDEHYDES
CARBOHYDRATES
HEXOSES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MONOSACCHARIDES
ORGANIC COMPOUNDS
PLANTS
SACCHARIDES
SYNTHESIS
550201* - Biochemistry- Tracer Techniques