Bacteriophage degradation of Klebsiella K44 polysaccharide: an n.m.r. study and chemical proof of the position of the acetate group.

Bacteriophages (phi) have been used to degrade polysaccharides into oligosaccharides containing one or more of their repeating units. The capsular polysaccharide from Klebsiella K44 contains an acetate group, and n.m.r. spectroscopy and chemical methods have been employed to prove its linkage to O-6 of the 4-linked glucose residue. Phage phi 44 was shown to be an alpha-glucosidase not influenced by the acetate moiety and thus able to depolymerize the polysaccharide into pentasaccharide repeating units, some of which contained acetate on O-6 of the reducing glucose residue. The two oligosaccharides were studied by 1H- and 13C-n.m.r. spectroscopy, and their spectra were compared with those of the native and the deacetylated polysaccharide. 13C-n.m.r. was a useful tool for locating the 6-linked acetate, the position of which was confirmed by the method of temporary protection using methyl vinyl ether. The importance of using bacteriophages to obtain oligosaccharides is highlighted by the better results obtained with the oligosaccharide in comparison to the polysaccharide, both in n.m.r. spectroscopy and the temporary protection method.