Purification and characterization of an extracellular agglutinin from Tricophyton rubrum with specificity towards sialic acid containing glycoconjugates.

An agglutinin, a monomeric glycoprotein with a molecular mass of about 6.5 kDa and containing 18% sugar has been purified to an apparent homogeneity from a 21 days old culture filtrate of an anthropophilic dermatophyte Tricophyton rubrum. It is a human blood group non-specific agglutinin which also agglutinates animal erythrocytes and Ehrlich ascites carcinoma and Sarcoma-180 cells. It is thermally stable and exhibits maximum activity at pH 8. Amino acid analysis shows a significant amount of glycine, with no cysteine. Glycoproteins inhibited the hemagglutination of the agglutinin, but not the simple sugars, including sialic acid. Fetuin is the most potent inhibitor among the glycoproteins tested. This inhibition gives a hint to binding with Galbeta1-3GalNAc or Galbeta1-4GlcNAc residue containing sialic acid at the terminal position with alpha 2-6 or alpha 2-3 linkage.