Partial characterization of the polyisoprenoid carrier of N-acetylglucosamine in Glycine max (soya bean)

Abstract

Dolichyl phosphate (C55) and dolichyl phosphate prepared from liver were incubated with an enzyme prepared from soya-bean protoplasts. They both stimulated the transfer of radioactivity from UDP-D-glucose to lipid, but the stimulation was greater with liver dolichyl phosphate. Liver dolichyl phosphate with the soya-bean enzyme stimulated the transfer of radioactivity from UDP-N-acetyl-D-[U-14C]glucosamine to acidic lipid. UDP-D-[U-14C]glucose and UDP-N-acetyl-D-[U-14C]glucosamine were used with the soya-bean enzyme to prepare the glycosylated-acid-lipid acceptor of each sugar. Mild acid hydrolysis revealed that the radioactivity in the lipid glucosylated from UDP-glucose was present exclusively as glucose. That in the lipid glycosylated from UDP-N-acetylglucosamine was present mostly as N-acetylglucosamine. The soya-bean acidic-lipid acceptors of glucose and N-acetylglucosamine were stable to both catalytic hydrogenation and treatment with hot aqueous phenol; they behaved in a similar way as authentic alpha-saturated glucosylated polyisoprenyl phosphates. The soya-bean acidic-lipid acceptors of glucose and N-acetylglucosamine were eluted as deoxycholate complexes from a Sephadex column. In comparison with glucosylated polyisoprenyl phosphates of known size, the patterns of elution indicated that both soya-bean lipids contained a polyisoprenoid chain of 18 isoprene units.

Transfer of Oligosaccharide to Protein from a Lipid Intermediate in Plants

“…The radioactivity was measured on 0.5-cm strips with a toluene-based scintillation fluid in a scintillation counter. (3,5). As judged by MS, the plant compound is very similar to or identical with animal dolichol phosphate (7).…”