The interaction between propranolol (PROP) and human serum albumin (HSA) was studied in the presence of dimethyl methylphosphonate (DMMP). DMMP is usually considered as a simulant for chemical warfare agents (CWAs). For this purpose fluorescence quenching, resonance light scattering (RLS), synchronous, three-dimensional fluorescence spectroscopy and molecular dynamics (MD) simulation were employed under physiological conditions. Fluorescence spectroscopy showed that DMMP could quench, and PROP increased intensity of the HSA fluorescence spectra. The presence of DMMP remarkably decreased binding constant of PROP to HSA. Therefore, by decreasing the amount of drugs transported to its target, the free drug concentration of the target would be raised, increasing the efficacy of the drug. The results of synchronous fluorescence and three-dimensional fluorescence spectra showed that the binding of PROP and DMMP to HSA induced conformational changes of HSA. According to molecular dynamics simulation results proposed that these ligands could interact with the HSA, with affecting the secondary structure of protein and with a modification of its tertiary structure.

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