PREPARATION AND PHYSICOCHEMICAL PROPERTIES OF GLYCOSYLATED DERIVATIVES OF PEA LEGUMIN

Neoglycolegumins were prepared by reductive alkylation of amino groups of pea legumin with various carbohydrates. The percentage of modification of amino groups was 84% with galactose, 59% with glucose, 49% with lactose, and 18% with galacturonic acid. Electrophoretic behavior and sedimentation studies showed that the glycosylation of legumin tends to decrease the aggregated forms observed for unmodified legumin, while partially dissociated forms appeared especially for legumin modified with galacturonic acid. The kinetics of glycosylation and the electrophoretic patterns indicated that all the amino groups did not react at the same rate. The higher glycosylation rate observed for the α-polypeptides suggests that they are more exposed to the protein surface than the β-polypeptides. Analyses of ultraviolet difference and circular dichroism spectra showed that, among the 35 nonaccessible tyrosyl residues in the unmodified legumin, only 4–7 residues became unburied after glycosylation. It is probable that the inner part of the neoglycoprotein keeps its close packed structure. © 1990, American Chemical Society. All rights reserved.