OBSERVATION OF UNIQUE CROSS-LINKED LATTICES BETWEEN MULTIANTENNARY CARBOHYDRATES AND SOYBEAN LECTIN - PRESENCE OF PSEUDO-2-FOLD AXES OF SYMMETRY IN COMPLEX TYPE CARBOHYDRATES (VOL 33, PG 5614, 1994)

The tetrameric lectin from Glycine max (soybean) (SBA) has been shown to cross-link and precipitate with N-linked multiantennary complex typ e oligosaccharides containing nonreducing terminal Gal residues (Bhatt acharyya, L., Haraldsson, M., and Brewer, C. F. (1988) Biochemistry 27 , 1034-1041). In the present study, negative stain electron micrograph s of the precipitates of SBA with a series of naturally occurring and synthetic multiantennary carbohydrates with terminal Gal or GalNAc res idues show the presence of highly ordered cross-linked lattices for ma ny of the complexes. The precipitates of SBA with a ''bisected'' and ' 'nonbisected'' N-linked biantennary complex type oligosaccharide conta ining Gal residues at the nonreducing termini show similar two-dimensi onal patterns. However, the pattern observed for the precipitates of a tetraantennary complex type oligosaccharide with SBA is distinct from those of the two biantennary carbohydrates. Furthermore, the precipit ates formed between the lectin and a synthetic O-linked biantennary (' 'cluster'') glycoside with terminal GalNAc residues show a pattern tha t is different from those above. Four biantennary pentasaccharide anal ogs of the blood group I antigen containing beta-LacNAc moieties at th e 2,3-, 2,4-, 2,6-, and 3,6-positions of the core Gal also showed orde red patterns in their precipitates with SBA. X-ray crystallographic da ta and mixed quantitative precipitation profiles of binary mixtures of the four analogs demonstrate that each analog possesses a unique cros s-linked lattice with the protein. A common structural feature of the naturally occurring and synthetic carbohydrates that show highly organ ized cross-linked lattices with SBA is the presence of a pseudo-2-fold axis of symmetry in each oligosaccharide relating the terminal bindin g epitopes on each arm. This suggests that the symmetry features of ce rtain naturally occurring branch chain oligosaccharides facilitate for mation of highly ordered, homogeneous cross-linked complexes with spec ific lectins.