A study of the interaction between bromopyrogallol red and bovine serum albumin by spectroscopic methods

The mechanism of binding of bromopyrogallol red (BPR) with bovine serum albumin (BSA) was investigated by fluorescence, absorption, circular dichroism (CD) and lifetime measurements. The analysis of fluorescence data indicated the presence of both dynamic and static quenching mechanism in the binding. Various binding parameters have been evaluated. The CD spectral data revealed the decrease in α-helical content of BSA from 70.7% (in free BSA) to 53.89% (in bound form) thereby indicating the conformational change in BSA upon binding. The thermodynamic parameters have also been evaluated. The binding average distance, r between the donor (BSA) and acceptor (BPR) was determined based on the Förster's theory and it was found to be 3.84 nm. The association constant of BPR–BSA decreased in the presence of common ions.