Substrate specificity of the glycanase activity associated with particles of Klebsiella bacteriophage no. 6.

A glycanase activity associated with the particles of Klebsiella bacteriophage No. 6 catalyses cleavage of O-beta-D-glycopyranosyl-(1 leads to 3)-4,6-O-(1-carboxyethylidene)-beta-D-mannopyranose linkages in Klebsiella serotype-6 capsular polysaccharide. Of 74 heterologous Klebsiella polysaccharides and two derivatives of the type-6 glycan, only the type-1 and type-57 polymers were additionally degraded by the phage-6 enzyme. The repeating units in the three substrates have a 1ax leads to 3eq, 1eq leads to eq-linked chain D-gluco- or D-galacto-pyranosyl residue in common (which constitutes the reducing end after glycanase action), and a carboxyl group on the next hexopyranosyl residue. Of the 72 polysaccharides not affected by the viral enzyme, at least the type-11 and type-21 glycans also contain the same homology of primary structure. This indicates that the conformation at the glycanase recognition-site also constitutes an important feature of the substrates.