Lectin-carbohydrate complex evaluation by chemiluminescence.

Abstract In order to characterize the affinity between specific carbohydrate-binding proteins such as lectins, a model is proposed to study these interactions using a polysaccharide membrane to simulate such adsorption. Here, lectin-carbohydrate interactions were chemiluminescently investigated using lectins conjugated to acridinium ester (AE) and polysaccharides composed of their respective specific carbohydrates. The lectin-AE conjugates were incubated with discs (0.0314–0.6358 cm 2 ) of phytagel, chitosan and carrageenan. The complex formation chemiluminescently detected followed the Langmuir isotherm from which constants were estimated. The association constant (K a ) and maximum binding sites on the membranes were 2.4 × 10 −7  M −1  ± 0.8 × 10 −7  M −1 and 1.3 × 10 −3  mol. mg −1 ± 0.3 × 10 −3  mol. mg −1 (Con A); 0.9 × 10 −6  M −1  ± 0.4 × 10 −6  M −1 and 0.021 × 10 −3  mol. mg −1 ± 0.003 × 10 −3  mol. mg −1 (WGA) and 2.0 × 10 −6  M −1  ± 0.9 × 10 −6  M −1 and 0.069 × 10 −3  mol. mg −1 ± 0.010 × 10 −3  mol. mg −1 (PNA). The proposed model might be useful to study binding affinity and estimate the amount of binding not limited by the sugar content in the membrane.