Dolichyl monophosphate and its sugar derivatives in plants.

A glucose acceptor was isolated from soya beans by extraction with chloroform/methanol (2:1, v/v), followed by DEAE-cellulose column chromatography of the extract. This acceptor could not be distinguished from liver dolichyl monophosphate by t.l.c. It could replace dolichyl monophosphate as a mannose acceptor with a liver enzyme and its glucosylated derivative could replace dolichyl monophosphate glucose as a glucose donor in the same system. These results, together with those already reported [Pont Lezica, Brett, Romero Martinez & Dankert (1975) Biochem, Biophys. Res. Commun. 66, 980-987], indicate that the acceptor from soya bean is a dolichyl monophosphate. Gel filtration of its glucosylated derivative on Sephadex G-75 in the presence of sodium deoxycholate indicated that the acceptor contained 17 or 18 isoprene units. An enzyme preparation from pea seedlings was shown to use endogenous acceptors to form lipid phosphate sugars containing mannose and N-acetylglucosamine from GDP-mannose and UDP-N-acetylglucosamine. Chromatographic and degradative techniques indicated that the compounds formed were lipid monophosphate mannose, lipid pyrophosphate N-acetylglucosamine, lipid pyrophosphate chitobiose and a series of lipid pyrophosphate oligosaccharides containing both mannose and N-acetylglucosamine. None of these compounds was degraded by catalytic hydrogenation, and so the lipid moiety in each case was probably an alpha-saturated polyprenol. The endogenous acceptors for mannose and N-acetylglucosamine in peas may therefore be dolichyl monophosphate, as has been found in mammalian systems

Oligosaccharides containing glucose and mannose in glycoproteins of the thyroid gland.

The glucose-containing oligosaccharides formed by calf thyroid slices incubated with radioactive glucose were studied. A compound soluble in chloroform/methanol/water, 1:1:0.3 (vol/vol), was found that was indistinguishable from the previously described glucose-containing dolichyl diphosphate oligosaccharide formed by liver microsomes. Glycopeptides were prepared by treating the glycoproteins with pronase, the amino acids were removed with alkaline borohydride, and the products were examined by paper electrophoresis and chromatography. A saccharide equal to that which occurs in the glucose-containing dolichyl diphosphate oligosaccharide could not be detected but glucose was found in oligosaccharides that seemed to be smaller by about three to five monosaccharide residues. The same results were obtained by direct treatment of the glycoproteins with alkaline borohydride

Studies on uridine-diphosphate-glucose

originalFil: Paladini, Alejandro C.. Instituto de Investigaciones Bioquímicas Fundación Campomar; ArgentinaFil: Leloir, Luis Federico. Instituto de Investigaciones Bioquímicas Fundación Campomar; ArgentinaBlanco y negro5 páginas en pdfLFL-PI-O-ART. Artículos científicosUnidad documental simpleAR-HYL-201