Protein-sugar interactions. Purification by affinity chromatography of limulin, an N-acyl-neuraminidyl-binding protein.

The lectin of Limulus polyphemus haemolymph agglutinates erythrocytes [l-4] and other cells [ 51. Neuraminic acid has been shown to be the specific ligand of this lectin. The lectin has been isolated by ultracentrifugation and preparative starch gel electrophoresis [6], by DEAE-Sephadex and gel filtration chromatography [7] and by ultracentrifugation, affinity and gel filtration chromatography [8]. Though the protein prepared by the last two methods [7,8] was homogeneous with respect to molecular weight, polyacrylamide gel electrophoresis and immunoelectrophoresis, we got three fractions by affinity chromatography. The first two fractions (Limulin I and II) did not agglutinate erythrocytes, but the third fraction (Limulin III) was very active. We wish to report the affinity chromatography purification of Limulin III and to show that Limulin binds O-glycosides of N-acyl-neuraminic acids more strongly than free N-acryl-neuraminic acids.