An insight of binding interaction between Tryptophan, Tyrosine and Phenylalanine separately with green gold nanoparticles by fluorescence quenching method

The present work describes spectroscopic interaction of individual of the three important amino acids Tryptophan (Trp), Tyrosine (Tyr) and Phenylalanine (Phe) with biologically prepared gold nanoparticles (GP). The obtained UV-vis spectrum implicated the formation of ground state complex between Trp, Tyr and Phe with GP. Gold nanoparticles can quench the intrinsic fluorescence of the said amino acids through static quenching process. The binding constant, binding site and corresponding thermodynamic parameters (Delta H, Delta S and Delta G) of the interaction system were calculated at different temperature. In all three cases binding constant K decreases with rise in temperature. The thermodynamic results revealed that the binding process is spontaneous; hydrogen bond and van der Waals was the main force to stabilize the complex in all three cases. Moreover, the Forster non-radiation energy transfer (FRET) theory has been applied to calculate the average binding distance between the above amino acids and GP. The result shows that binding distance has been <7 nm suggested energy transfer takes place between said amino acids and GP. (C) 2017 Elsevier GmbH. All rights reserved.