Binding of chlorpyrifos and cypermethrin to blood proteins

The features of two insecticides (chlorpyrifos and cypermethrin) binding to two blood proteins, bovine serum albumin (BSA), and bovine hemoglobin (BHb), were investigated via the fluorescence method. The results revealed that both insecticides caused the fluorescence quenching of BSA and the fluorescence enhancement of BHb. A new parameter (F-E), i.e., the fluorescence intensity when adequate insecticide was added, was introduced to obtain the association constant (K-A) and the Dumber of binding sites (n). K-A and n of chlorpyrifos and cypermethrin binding to BSA were 2. 99 X 10(5) and 5.22 x 10(5) L mol(-1), 1.25 and 0.78, respectively. K-A and n of chlorpyrifos and cypermethrin binding to BHb were 2.94 x 10(4) and 2.48 x 10(4) L mol(-1), 1.75 and 2.19, respectively. In conclusion, chlorpyrifos and cypermethrin could bind to BSA and BHb, and the binding of both insecticides to BSA was significantly stronger than that of insecticides to BHb. These could affect the distribution, metabolism, and excretion of insecticides. (c) 2005 Elsevier Inc. All rights reserved.