Spectroscopic investigations of pentobarbital interaction with human serum albumin

The interaction between pentobarbital and human serum albumin has been investigated. The basic binding interaction was studied by UV-absorption and fluorescence spectroscopy. From spectral analysis pentobarbital showed a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The binding constant (k) is estimated at 1.812 × 104 M−1 at 293 K. FT-IR spectroscopy with Fourier self-deconvolution technique was used to determine the protein secondary structure and drug binding mechanisms. The observed spectral changes of HSA–pentobarbital complex indicate a larger intensity decrease in the absorption band of α-helix relative to that of β-sheets. This variation in intensity is related indirectly to the formation of H-bonding in the complex molecules, which accounts for the different intrinsic propensities of α-helix and β-sheets.