咖啡酸与牛血红蛋白的相互作用及抗氧化研究

Interaction of Caffeic Acid with Bovine Hemoglobin and Its Antioxidation Effects

为研究不同溶剂体系对咖啡酸与牛血红蛋白相互作用及其抗氧化性的影响。在水溶液、10%乙醇和10%二甲基亚砜体系中,通过紫外光谱、荧光光谱、同步荧光光谱、红外光谱和对DPPH自由基和ABTS+自由基清除能力的测定,研究咖啡酸和牛血红蛋白的相互作用及其对咖啡酸抗氧化性的影响。结果表明,在3种不同溶剂体系中,随咖啡酸浓度的增加,其对牛血红蛋白的荧光猝灭均逐渐增强,猝灭方式和相互作用均分别为静态猝灭和疏水作用,结合位点更靠近Trp残基,牛血红蛋白空间构象更加伸展。在10%乙醇和10%二甲基亚砜体系中,牛血红蛋白的酰胺I带和酰胺II带发生明显红移且二级结构由α-螺旋逐渐向β-折叠转变。牛血红蛋白-咖啡酸复合物显著降低了咖啡酸对DPPH自由基的清除率,但对ABTS+自由基的清除率无明显影响。在3种不同溶剂体系中,咖啡酸均可使牛血红蛋白空间构象发生改变,同时牛血红蛋白也会不同程度地影响咖啡酸的抗氧化性。

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 fromα-helix toβ-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.