Interaction of [(piro[(2R,3R,4S)-4-benzyloxy-2,3-iso-propylidenedioxy-1-oxacyclopentane-5,5'-(2-nitromethylene-1,3-diazacyclohexane)] with bovine serum albumin

The interaction of a novel pesticide, NMD (spiro[(2R,3R,4S)-4-benzyloxy-2,3-iso-propylidenedioxy-1-oxacyclopentane-5,5'-(2-nitromethylene-1,3-diazacyclohexane)]), with bovine serum albumin (BSA) has been investigated by using absorption, fluorescence, and circular dichroism (CD) spectroscopy methods. Quenching of the fluorescence of BSA has been observed in the presence of NMD. The binding parameters were determined using Stern-Volmer equation. From the thermodynamic parameters calculated according to the van't Hoff equation, the enthalpy change ΔH, and entropy change ΔS were found to be -2.71 kJ mol-1 and 82.56 J mol-1 K-1, respectively. These values suggested that, apart from an initial hydrophobic association, the complex is held together by van der Waals interactions and hydrogen bonding. These results provided a quantitative understanding of the binding of NMD to BSA, which is important in understanding its toxicity in vertebrates.