Interaction of 3', 4'-Dideoxykanamycin B and Submaxillary Mucin

Abstract

The interactions of an aminoglycoside antibiotic, 3', 4'-dideoxykanamycin B (DKB), with submaxillary mucin were investigated by equilibrium dialysis and affinity chromatography.
DKB binds to mucin and forms a complex of low solubility. This binding was dependent on the pH and ionic strength. Scatchard plot analysis showed that mucin had one class of binding sites for DKB. The binding coefficient was 1.30×10^-5M and the concentration of binding sites was 0.243 μmol per mg of mucin at 25°C. The binding of DKB to mucin was inhibited in the presence of Ca²⁺ or amines, such as ethylenediamine, spermidine and glucosamine. The N-pentaacetyl derivative of DKB did not bind to mucin. The binding of DKB to asialomucin was decreased. After binding to a DKB-conjugated Sepharose 4B column, a small amount of mucin was eluted with NaCl solution and a large amount of mucin was eluted with N-acetylneuraminic acid solution.
These results suggest that the binding of DKB to mucin involves an ionic interaction between the amino groups of DKB and the carboxyl groups of the sialic acid residues of submaxillary mucin.