EXPERIMENTAL AND THEORETICAL ECD STUDY OF THE 7-METHOXYCOUMARIN-3-CARBOXYLIC ACID BINDING TO BSA

We report induced circular dichroism (ICD) experimental data on 7-methoxycoumarin-3-carboxylic acid(MCCA)binding to bovine serum albumin(BSA), correlated with electronic circular dichroism (ECD) simulated spectra. The induced chirality and corresponding dichroic signal can be explained by the twisting and steric hindrance of the bound MCCA ligand in the protein pocket. A more general view on the influence that the two intramolecular degrees of freedom of the ligand have on the features of the ECD spectrum is provided, as well as a method to estimate the bound conformation of the ligand. The dependence of the theoretically calculated rotatory strengthon the dihedrals between different molecular fragments is discussed. Good correlations with the ICD experimental data are obtained