Interaction of Synthetic Pyrethroid Insecticide Deltamethrin with Human Alpha-2-Macroglobulin: Spectroscopic and...

Deltamethrin (DLM) is a commercial insecticide of the synthetic pyrethroid family that is used to control disease-causing insects and vectors. When humans are exposed to the fumes or aerosols of DLM, it enters the body via cuticular absorption and reacts with proteins and other biomolecules.

Alpha-2-macroglobulin (α₂M) is a serum proteinase inhibitor that also carries out receptor- mediated endocytosis of extracellular substances. This study was done to decipher the structural and functional alterations of α₂M by DLM.

Various spectroscopic techniques, including UV absorption and fluorescence spectroscopy, binding studies, and molecular docking, were used to characterize the interaction of DLM with α₂M. The affinity constant was calculated from the Stern-Volmer equation using fluorescence data.

The UV-Vis and fluorescence spectral studies indicated the formation of a complex between α₂M and DLM. Thermodynamically, the interaction was found to be spontaneous with ΔG = -4.23 kcal/mol. CD spectra suggested a change in the secondary structure of the protein from β to α helical content with increasing concentration of DLM. The molecular docking study by Autodock Vina established the interaction of DLM with Glu-926, Ala-1103, Ala-1108, Val-1116, Asn-1159, Glu-1220, Leu-1261, Thr-1272, Ile-1390, Pro-1391, Lys-1393, Val-1396, Lys-1397, Thr-1408, Glu-1409, Val-1410, Ser-1411, Ser-1412, and Asn-1413 with an improved docking score of -6.191 kcal/mol. The binding was carried out in the vicinity of the receptor-binding domain at the C-terminal of α₂M.

The decrease in the functional activity and structural changes of protein after binding with DLM has a significant effect on human α₂M. The information may be useful for exploring the role of DLM in a clinical chemistry laboratory.