Abstract:The effects of different solvents on the interaction of bovine hemoglobin（BHb）and caffeic acid（CA）and its antioxidant effects were investigated.The interaction between BHb and CA was studied in dH2O，10% ethanol and 10% dimethyl sulfoxide（DMSO）using ultraviolet spectrum，fluorescence spectrum，synchronous fluorescence and infrared spectroscopy.The antioxidant effects of CA were also investigated using DPPH and ABTS+radical scavenging methods.The results showed that the fluorescence quenching effect of CA on BHb increased gradually with an increase in CA concentration.The quenching mechanism and interaction force were static quenching and hydrophobic force，respectively.Binding sites were much closer to tryptophan residue and BHb became more unfolded in three different systems.Evident blue-shift occurred in amide I and II bands of BHb，and its secondary structure changed from α-helix to β-sheet gradually in 10% ethanol and 10% DMSO.The scavenging effect of BHb-CA on DPPH decreased considerably but had no substantial effect on the ABTS+radical in three different solvents.The results demonstrated that the conformation of BHb can be changed by CA and that the antioxidation of CA can be influenced by BHb in different conditions.