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 a-helix relative to that of b-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 a-helix and b-sheets.This work is supported by the German Research Foundation
DFG Grant No. DR228/24-2
