Conformational Analysis of a Complex Between Dolichos biflorus Lectin and the Forssman Pentasaccharide Using Transferred NOE Build-Up Curves

Abstract

A complex between the Forssman pentasaccharide α-D-GalNAc-(1→3)-β-D-GalNAc-(1→3)-α-D-Gal-(1→4)-β-D-Gal-(1→4)-D-Glc and the seed lectin from Dolichos biflorus was studied using 2D transfer-NOESY (trNOESY) experiments. Experimental transfer-NOE (trNOE) build-up curves of the complex were compared to theoretical values from a complete relaxation and conformational exchange matrix (CORCEMA) calculation. The dissociation constant and the off-rate for the complex formation were determined by fitting experimental intra-glycosidic trNOE build-up curves to corresponding theoretical curves. Atomic coordinates for the complex were taken from a previous homology-modeling study of a complex between the disaccharide fragment α-D-GalNAc-(1→3)-β-D-GalNAc and D. biflorus lectin. The comparison of experimental and theoretical inter-glycosidic trNOEs expands our previous qualitative NMR study and allows further assessment of the quality of the homology modeling study.