Wistaria sinensis agglutinin: purification, carbohydrate specificity, and characterisation of the combining site.

A 2-acetamido-2-deoxy-D-galactose-binding agglutinin from Wistaria sinensis seeds, purified by affinity chromatography on a 2-acetamido-2-deoxy-D-galactose-starch conjugate, was homogeneous as judged by poly(acrylamide) disc gel electrophoresis. It had a mol. wt. of 66,000 (gel filtration on Sephadex G-150); on electrophoresis on SDS-poly(acrylamide) gel in the presence of 2-mercaptoethanol, it dissociated into sub-units of mol. wt. 34,000, suggesting the agglutinin to be a dimer; and it was a glycoprotein containing 4.8% of carbohydrate. It agglutinated several vertebrate erythrocytes, including human regardless of the blood group. In hapten-inhibition assays, 2-acetamido-2-deoxy-D-galactose and its glycosides were found to be better inhibitors than D-galactose and its glycosides, but N-acetyl-lactosamine was the most potent inhibitor. The binding involved HO-3,4 of the haptens and HO-2 partially.