Specificity of the fucose-binding lectin ofPseudomonas aeruginosa

PA-II lectin of Pseudomonas aeruginosa, purified by affinity chromatography, was examined for its relative affinity to various carbohydrates using equilibrium dialysis and hemagglutination inhibition tests. This lectin was found to exhibit a high affinity for l-fucose and its derivatives. Among them, p-nitrophentl-α-l-fucose was the strongest inhibitor, followed by l-fucose →l-fucosylamine l-galactose →d-mannose →?→d-fructose. The association constant (Ka) of l-focuse for PA-II was 1.5 × 106· M−1 and the number of the l-fucose-binding sites per protein subunit was approximately 1. The Ka of d-mannose for PA-II was 3.1 × 10−2· M−1 and a value of 0.84 was obtained as the number of its binding sites per mole protein subunit.