title: Biosynthesis of pentosyl lipids by pea membranes.
abstract: Pea membranes were incubated with UDP-[14C]xylose or UDP-[14C]arabinose and sequentially extracted with chloroform/methanol/water (10:10:3, by vol.) and sodium dodecyl sulphate (2%, w/v). An active epimerase in the membranes rapidly interconverted the two pentosyl nucleotides. Chromatographic analysis of the lipid extract revealed that both substrates gave rise to xylose- and arabinose-containing neutral lipids, xylolipid with properties similar to a polyisoprenol monophosphoryl derivative, and highly charged lipid-linked arabinosyl oligosaccharide. When UDP-[14C]pentose or the extracted lipid-linked [14C]arabinosyl oligosaccharide were used as substrates, their 14C was also incorporating into sodium dodecyl sulphate-soluble and -insoluble fractions as major end products. Polyacrylamide-gel electrophoresis of sodium dodecyl sulphate-soluble products indicated the formation of mobile components with Mr values between 40 000 and 200 000 (Sepharose CL-6B). The lipid-linked [14C]arabinosyl oligosaccharide possessed properties comparable with those of unsaturated polyisoprenyl pyrophosphoryl derivatives. It was hydrolysed by dilute acid to a charged product (apparent Mr 2300) that could be fractionated in alkali. It was degraded to shorter labelled oligosaccharides by slightly more concentrated acid and eventually to [14C]arabinose as the only labelled component. Susceptibility to acid hydrolysis, and methylation analysis, indicated that the oligosaccharide contained approximately seven sequential alpha-1,5-linked arabinofuranosyl units at the non-reducing end. Several acidic residues appear to be interposed between the terminal arabinosyl units and the charged lipid.
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002850:Chromatography, Gel; D002854:Chromatography, Paper; D002855:Chromatography, Thin Layer; D004591:Electrophoresis, Polyacrylamide Gel; D007887:Fabaceae / Q000378:metabolism; D007700:Kinetics; D008055:Lipids / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000096:biosynthesis; D010429:Pentoses / Q000378:metabolism; D010944:Plants / Q000378:metabolism*; D010946:Plants, Medicinal; D014539:Uridine Diphosphate Sugars / Q000378:metabolism; D014540:Uridine Diphosphate Xylose / Q000378:metabolism
chemical_list: D008055:Lipids; D008070:Lipopolysaccharides; D010429:Pentoses; D014539:Uridine Diphosphate Sugars; C023023:lipid-linked oligosaccharides; C040817:uridine diphosphate arabinose; D014540:Uridine Diphosphate Xylose