Purification and characterization of an extracellular lectin from Mycobacterium smegmatis

Mycobacteria exist naturally in aggregated form and pathogenic strains colonize macrophages. A lectin has been isolated from the culture broth of M. smegmatis, which may, possibly, have an important role in either or both of these phenomena. The lectin of Mr 12,000-14,000 agglutinates erythrocytes from different species, and agglutination is reversed by arabinogalactan isolated from mycobacteria, as well as by yeast mannan. It has a pI of 5.5 and is rich in aspartic and glutamic acid residues.