Protein and Bilirubin(BR) are the main components in animal bile. When the metabolization is disordered

the unnecessary and free bilirubin can combine with some proteins to form compositions and produce toxin. To learn the mechanism of toxicity

the effects of bilirubin on the molecular structure of Hemoglobin(Hb) and the means of their combination were studied by fluorescence and UV absorption spectra. It was shown that BR can quench the fluorescence of Hb extently

which decreased the fluorescent intensity of tryptophan(Try) at 330 nm and the peak at 410 nm disappeared; at pH 9.4 BR can bind with Hb in cooperative actions of nonelectrostatic attraction

e g. Hydrophobic action

Van der Waals force. The intensity declinded with the delay of time. The group of -NH

2

on the Try residue of Hb molecule reacted with two -COOH groups

and formed a complex with curly structures. The spectra can vary with temperature

the conformation of BR changed from Z-Z to Z-E or E-Z

which caused complex structures. It showed two peaks at 350 nm and 406 nm induced by dipyrrole chromphoses of BR

the absorption fissions occurred in Hb UV spectra. Therefore

the present of free bilirubin molecules damaged the structure of Hb molecule and the spectra appeared different. It is less reported about the interaction of Hb and BR at present

the discussions in this paper provide experimental information for the study on medicine and biochemistry

and also offer some theoretical bases for the relation between biological macromolecules and organic micromolecules.