Binding study of lysozyme with Al(III) using chemiluminescence analysis

Abstract

The binding behavior of lysozyme with Al(III) is described using luminol as a luminescence probe by flow injection-chemiluminescence (FI-CL) analysis. It was found that the CL intensity of the luminol-lysozyme reaction could be markedly enhanced by Al(III), and the increase in CL intensity was linear with the Al(III) concentration over the range 0.3-30.0 pg mL(-1) , with a detection limit of 0.1 pg mL(-1) (3σ). Based on the interaction model of lysozyme with Al(III), lg[(I - I0 )/(2I0 - I)] = lgK + nlg[M], the binding constant K = 6.84 × 10(6) L mol(-1) and the number of binding sites (n) = 0.76. The relative standard deviations were 3.2, 2.4 and 2.0% for 10.0, 20.0 and 30.0 pg mL(-1) Al(III) (n = 7), respectively. This new method was successfully applied to continuous, quantitative monitoring of picogram level Al(III) in human saliva following oral intake of compound aluminum hydroxide tablets. It was found that Al(III) in saliva reached a maximum of 101.2 ng mL(-1) at 3.0 h. The absorption rate constant ka , elimination rate constant k and half-life time t1/2 of Al(III) were 1.378 h(-1) , 0.264 h(-1) and 2.624 h, respectively.