Recognition of 2-keto-3-deoxyoctonate in bacterial cells and lipopolysaccharides by the sialic acid binding lectin from the horseshoe crab Carcinoscorpiusrotundacauda

The sialic acid binding loctin carcinoscorpin agglutinates $\text{Escharichia}\text{coli}\text{K12}\text{and}\text{Salmonella}\text{minnesots}$ R595 cells. This interaction can be inhibited by the saccharides namely 2-keto-3-deoxyoctonate and the disaccharide D-(N-acetylneuraminyl) (2→6)2-acetamide-2-deoxy-D-galactitol. N-acetylneuraminic acid is shown to be a poor inhibitor. The same behaviour is seen when purified lipopolysaccharides from these two Gram negative bacteria are used. $\text{Vibrio}\text{cholerae}$, a Grum negative bectarium devoid of 2-keto-3-deoxyoctonate and $\text{Staphylococcus}\text{sureus}$ a typical Gram positive bacterium failed to agglutinate in the presence of the lectin. The results suggest that the 2-keto-3-deoxyoctonate residues might represent the physiological substrate for the sialic acid binding lectin from the horseshoa crab.