Transfer of Oligosaccharide to Protein from a Lipid Intermediate in Plants

Abstract

A lipid-bound oligosaccharide was isolated from pea (Pisum sativum) cotyledons incubated with [¹⁴C]mannose. The oligosaccharide moiety appeared to be identical with the one obtained from rat liver, known to contain three glucoses, nine mannoses, and two N-acetylglucosamines, and to be involved in protein glycosylation.

Enzymes obtained from soya (Glycine max) roots and developing pea cotyledons were found to catalyze the transfer of oligosaccharide from the lipid intermediate to endogenous protein. The enzymes require Mn²⁺ and detergent for activity. Evidence is presented indicating that the lipid-bound oligosaccharide with three glucoses is transferred faster than that with less. Some of the peripheral mannoses could be removed without affecting the rate of transfer.

The protein-bound oligosaccharide, formed by incubation of whole cotyledons or by transfer with the enzyme preparation, could be released by protease and endo-β-N-acetylglucosaminidase treatment, as expected for an asparagine-bound high mannose oligosaccharide.

1

Career Investigator of the Consejo Nacional de Investigaciones Cientificas y Tecnicas, Argentina.

2

Fellow of the Consejo Nacional de Investigaciones Cientificas y Tecnicas, Argentina.