Analyzing organophosphate pesticide-serum albumin binding interaction: a combined STD NMR and molecular docking study

Abstract

In Vitro analysis of the interaction of organophosphate pesticides (OP) with bovine serum albumin (BSA) is crucial to understand their potential effects at the molecular level. In this context, we have employed Saturation Transfer Difference (STD) NMR experiments in conjunction with molecular docking studies to unravel the binding interaction of the OP chlorpyrifos (CPF), diazinon (DZN) and parathion (PA) in solution. The relative STD (%) suggested the detailed epitope mapping of these OP with BSA while the concentration-dependent STD NMR studies were performed to obtain the complex dissociation constant (K_D) of the OP-BSA complexes; K_D=1.81 × 10⁻⁴ M, 1.30 × 10⁻³ M and 1.11 × 10⁻³ M for CPF, DZN and PA were extracted respectively. Similar binding modes were identified for all the three OP using STD site-marker experiment. ITC experiments were performed as a complementary method that revealed a high binding affinity of OP-BSA complexes through non-covalent interaction. Molecular docking confirmed the possible interacting chemical groups of OP-BSA complexes. These significant results furnish valuable information about the toxicity risk of OP to proteins.

Communicated by Ramaswamy H. Sarma

Keywords:

• STD NMR
• group epitope mapping
• dissociation constant
• competition binding
• molecular docking

Acknowledgements

We thank MHRD, Govt. of India and IIT Jodhpur for providing student fellowship and contingency. The authors gratefully acknowledge a spectrometer grant to IIT Jodhpur from DST, India, and also thank the Department of Chemistry; IIT Jodhpur for other experimental facilities.

Disclosure statement

No potential conflict of interest was reported by the author(s).