About the Lectin

The hemolymph of the California coastal crab, Cancer antennarius, contains a lectin with a specificity for only two acetylated forms of sialic acid. Sialic acid is a generic term for derivatives of N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). The crab lectin shows a very narrow specificity for sialic acid when compared with other sialic acid binding lectins. Agglutination reactions with erythrocytes from different species shows the high degree of specificity of the crab lectin. Crab serum will agglutinate specifically horse, rabbit, mouse, and rat erythrocytes which contain O-acetyl sialic acids. It will not agglutinate human, monkey, pig, cow, guinea pig, sheep, or goat erythrocytes, which do not contain these forms of sialic acid 1 . The crab lectin requires calcium for binding to occur. The lectin binds optimally between pH 6.5-7.5, and does not bind above pH 8.0. Lyophilized preparations are reportedly stable for 9 months when stored at -20°C. However, the crude lectin supplied by EY Laboratories is supplied as a liquid. The pure lectin may also be stored frozen in the presence of 40% glycerol. Lectin activity is inhibited by sulfhydryl blockers but not by reducing agents 2 . The lectin has been used to identify o-acetyl gangliosides in human melanomas 3 . Please contact EY Laboratories for a copy of reference #4.


  1. Ravindranath, M. H., et al. (1985). J. Biol. Chem.260 : 8850-8856.
  2. Ravindranath, M. H., et al. (1987). Meth. Enzym.138 : 520-527.
  3. Ravindranath, M.H., et al. J. Biol. Chem. 263 : 2079-2086.
  4. Biotech: Sialic Acid and Related Products. Summer 1991.Published by EY Laboratories, Inc.

Product Characteristics

Buffer 0.05M Tris – 0.1M NaCl – 0.01M CaCl2, pH 7.2 containing 0.05% BSA.
Blood Group Horse and rabbit erythrocytes. Will not react with human cells.
Inhibitory Carbohydrate 9-O-acetyl sialic acid and 4-O-acetyl sialic acid.
Molecular Weight 37,000 Da as determined by SDS-PAGE. 70,000 Da under non-reducing conditions.
Caution The lectin adsorbs readily to glass and metal surfaces. For extended storage it should be kept in a plastic container with the addtion of BSA.