Investigation of the i̇nteraction of propazine and quinoxyfen with bovine serum albumin using spectrofluorimetric and computational techniques

In this thesis, it is aimed to examine the interactions of Propazine (PRO) and Quinoxifen (QUI), two pesticides that are widely used both to regulate the development of agricultural products and to protect them against various pests, with bovine serum albumin (BSA), which is the main carrier protein in the circulatory system, using fluorescence spectroscopy and calculations techniques. The results from fluorescence and absorption spectroscopy confirmed the complexation between PRO/QUI and BSA. The decrease in KSV values with increasing temperature showed that the PRO/QUI-induced quenching of BSA fluorescence is static quenching. At room temperature, the binding affinities of pesticides with BSA were Kf=3,63 × 10-3 M-1 for the PRO–BSA complex; For the QUI–BSA complex Kf =5,80 × 102 M-1. Relatively lower binding constant values were observed at increasing temperatures. Quantitative evaluation of thermodynamic data (ΔS= – 0,05 kJ mol–1 K–1, ΔH = – 103,45 kJ mol–1 for PRO-BSA complex and ΔS= + 0,01 kJ mol–1K–1, ΔH = – 12,84 kJ mol–1 for QUI-BSA complex) was supported in agreement with the results of molecular docking. The results showed that van der Waals interactions and hydrogen bonds are more effective in the formation of PRO-BSA and QUI-BSA complexes. Molecular docking results of PRO and QUI binding to BSA at the binding sites showed that both PRO and QUI can form more stable interactions at binding site I of BSA and QUI exhibited a higher affinity in site I compared to PRO.