Analysis of Binding Interaction between N,N-Bis (Phosphinomethyl) Amines as a New Class of 1-Aminophosphinic Acids and Bovine Serum Albumin Using Fluorescence Spectroscopy

Abstract

C2-symmetric N,N-bis(phosphinomethyl) amines have been synthesized and their interaction with bovine serum albumin (BSA) was investigated using fluorescence quenching technique. The fluorescence quenching of BSA during its binding to C2-symmetric N,N-bis(phosphinomethyl)amines molecules indicated the occurrence of energy transfer between ligand and protein. The experimental results showed that the formation of aminophosphinic acid-BSA complex and non-radiative energy transferring result in the fluorescence quenching. The binding parameters including binding constant KA and the corresponding thermodynamic parameters were calculated at different temperatures. The thermodynamic investigation showed that the binding process of the C2-symmetric N,N-bis(phosphinomethyl)amines molecules to BSA was a spontaneous molecular interaction procedure in which Gibbs free energy decreased and entropy increased. The hydrophobic interaction force plays a major role in stabilizing of the C2-symmetric N,N-bis(phosphinomethyl)amine-BSA complex. The synchronous fluorescence spectroscopy was used to study the effect of the C2-symmetric N,N-bis(phosphinomethyl)amine on the conformation of BSA. The results obtained from synchronous fluorescence spectra showed that the C2-symmetric N,N-bis(phosphinomethyl)amines did not cause considerable conformational changes in BSA.