10442
J. Phys. Chem. B 2010, 114, 10442–10450
Reverse Micelle Induced Flipping of Binding Site and Efficiency of Albumin Protein with an Ionic Styryl Dye Dibakar Sahoo, Prosenjit Bhattacharya, and Sankar Chakravorti* Department of Spectroscopy, Indian Association for the CultiVation of Science, JadaVpur, Kolkata 700032, India ReceiVed: April 1, 2010; ReVised Manuscript ReceiVed: July 6, 2010
The effect of reverse micelle environment on the binding mechanism of 2-(4-(dimethylamino)styryl)-1methylpyridinium iodide (DASPMI) with Bovine Serum Albumin (BSA) compared with that in buffer solution has been investigated in this paper with the help of steady state and time-resolved emission spectroscopy along with molecular docking to have a correct picture about binding. The binding of DASPMI with attachment efficiency of 30% and 70% at site I (subdomain IIA) and site II (subdomain IIIA) of BSA, respectively, in buffer solution gets reversed inside a reverse micelle. The bigger cavity size of site II in buffer solution ushers the dye with increased attachment efficiency and in reverse micelle change in π-stacking and hydrophobic interaction control the attachment efficiency. The calculated Fo¨rster distance gets curtailed as the environment changes from buffer to reverse micelle. The binding becomes stronger with a smaller gap between the probe and Trp-214 inside the reverse micelle than that in buffer solution. Introduction Reverse micelles are self-organized aggregates formed by surfactants in organic solvent, and nanometer-sized water pools are formed by the solubilization of water in their polar cores. The reverse micelles that are mostly with spherical shape are usually formed in ternary surfactant-water-organic solvent mixtures including surfactants (
