A valuable way for understanding the relationships between lysozyme and cephalosporin analogues by flow injection chemiluminescence

Abstract

The photochemical reaction mechanism of lysozyme with cephalosporin analogues was investigated with luminol used as a luminescence probe by flow injection chemiluminescence. It was found that Glu35 and Asp52 of lysozyme accelerated the rate of excited 3-aminophthalate electrons transferring and enhanced the chemiluminescence signal of luminol, producing steady-state chemiluminescence in the flow injection system with relative standard deviations less than 3.0%. It was also found that cephalosporin analogues could enter into the site of Trp62 in lysozyme forming 1 : 1 complex which leads to a conformational change of lysozyme, giving the effect of chemiluminescence quenching from luminol–lysozyme. Based on the photochemical behavior of luminol/lysozyme and cephalosporin, a model of lysozyme–cephalosporin interaction, lg[(I₀ – I)/I]=lgK_D + nlg[D], was established. Using the proposed model, the interaction parameters and the binding ability of lysozyme with cephalosporin were successfully obtained, and the results agreed very well with the results obtained by fluorescence.