Purification and partial characterization of a K99-antigen associated adhesin in Escherichia coli (637 strain)

The K99-antigen associated adhesin in Escherichia coli (637 Strain) has been purified to homogeneity by using conventional chromatographic procedures. Sodium deoxycholate was used in the precipitation steps to avoid hydrophobic interactions between the fimbriae and other membrane-associated components. Homogeneity of the purified adhesin was assessed by electrophoresis, isoelectrofocusing, analytical gel filtration and immunoprecipitation against K99 specific antiserum, being homogeneous in all cases. The purified adhesin is composed of protein sub-units with a molecular weight of 18,900 +/- 950 daltons. No sugars were detected in the molecule. The molecular weight of the adhesin was higher than 2 X 10(6) daltons, and its isoelectric point was estimated to be about 9.45.