Investigation of the interactions of dichlorprop, carbofuran, amitrol and diquat with human serum albumin protein by spectrofluorimetric method

In this study, the interactions of human serum albumin (HSA) protein, the most abundant protein in human blood plasma, with dichlorprop (DCP), carbofuran (CF), amitrol (AR) and diquat (DQ) pesticides were investigated by fluorescence and synchronous flouroscence spectroscopy. Fluorescence measurements were carried out at four different temperatures (288.15 K, 298.15K, 310.15 K and 318.15 K). Fluorescence measurements proved that there were interactions between HSA and pesticides except HSA-AR system. Stern-Volmer quenching constant, quenching rate constant, binding constant, number of binding site and thermodynamic parameter (?H, ?S and ?G) values were calculated for the binding processes of HSA-DCP, HSA-CF and HSA-DQ systems.Quenching mechanism for the binding process of DCP to HSA protein was static quenching mechanism. Binding constants for HSA-DCP system at 288.15 K, 298.15 K,300.15 K ve 318.15 K were found to be 7.48x103 M-1, 6.62 x103 M-1, 6.36 x103 M-1 and5.39 x103 M-1, respectively. Furthermore, there was only one binding site for DCP on HSA protein. Thermodynamic parameters of HSA-DCP system showed that driving force for binding process was electrostatic interaction. As the temperature of solution was increased from 288.15 K to 318.15 K, a decrease from 3.38x103 M-1 to 1.29x103 M-1 in the binding constant of HSA-CF system was observed and the number of bindingsite decreased slightly. Upon investigation of thermodynamic parameters, the main driving force of HSA-CF complex formation was found to be hydrogen bonding andvan der Waals forces. At 288.15 K and 318.15 K, the value of binding constant for HSA-DQ system were calculated to be 4.04x103 M-1 and 2.36x103 M-1, respectively. For this system, the number of binding site was found to be 1 approximately. Additionally, thermodynamic parameters showed that the binding process of DQ to HSA protein occurs spontaneously under the influence of electrostatic interactions.KEYWORDS: Human serum albumin, dichlorprop, carbofuran, amitrol, diquat,fluorescence spectroscopy.