Biophysical Studies on the Interaction of Cationic Urethane Gemini Surfactant with Insulin

The interaction of cationic urethane gemini surfactant, having two methylene units in spacer (C2), with insulinwas studied in phosphate-buffered saline PBS, pH 7.4, at 25 C as a function of surfactant concentration. The investigationdealt with fluorescence spectroscopy, in which the Stern-Volmer plot of acrylamide quenching experiment was studied. Thevalues of F0/F versus acrylamide concentration were depicted, where F0 and F were the fluorescence intensity in theabsence and presence of acrylamide. Results show that the slope of the Stern-Volmer plot decreases continuously uponincreasing the surfactant concentration. This observation indicates the progressive restricted accessibility of tyrosines to theenvironment, which is the consequence of either increasing the helical content of the protein or shielding effect of thehydrophobic interior of the nanomicelles.

Keywords:

Insulin , acrylamide , fluorescence spectroscopy , quenching