Absorption and emission spectral studies of bilirubin IXα complexes with sodium taurocholate in aqueous buffer, pH 8.0

Abstract

The absorption and fluorescence emission properties of (4Z, 15Z)-bilirubin IXα and xanthobilirubic acid in aqueous buffer at pH 8.0 and in the presence of the bile salt sodium taurocholate in the concentration range 1–40 mmol dm^–3 have been measured. The results are consistent with the formation of a complex in which an intramolecularly hydrogen-bonded conformer of bilirubin is bound in a hydrophobic microenvironment of a taurocholate aggregate, and in which molecular rotations and vibrations of the pigment are relatively unrestrained.