7-羟基香豆素与三种芳香族氨基酸作用的荧光光谱研究

Study of Interaction of Umbelliferone with Three Aromatic Amino Acids by Fluorescence Spectroscopy

运用荧光光谱和紫外光谱研究7-羟基香豆素UBM分别与色氨酸Trp,酪氨酸Tyr和苯丙氨酸Phe三种芳香族氨基酸的相互作用。结果表明在模拟人体生理条件下,UMB能引起上述氨基酸发生荧光猝灭,最大猝灭波长依次为347,303和282nm,猝灭机制均为静态猝灭,相互之间均以摩尔比1:1形成了复合物,且得到两种温度下UMB与Trp,Tyr和Phe反应的表观平衡常数Kc分别为298.15K时2.993×106,7.858×104和1.186×103 L.mol-1,310.15K时2.702×104,1.063×105和8.352×103 L.mol-1。热力学函数变化表明UMB与以上三种氨基酸结合作用较强,其中UMB-Trp相互作用力是氢键或范德华力,UMB-Tyr和UMB-Phe相互作用主要以疏水作用为主,同时都可能存在偶极-偶极之间的相互作用。

The interaction between umbelliferone（UMB）with tryptophan（Trp）,tyrosine（Tyr）and phenylalanine（Phe）was studied by using fluorescence（FS）and ultraviolet（UV）spectroscopy.The results show that UMB can strongly quench the fluorescence of the three aromatic amino acids with the maximum quenching wavelengths at 347,303and 282nm,respectively.Data analyses based on the Stern-Volmer curve and the UV spectroscopy show that static quenching occurred through the formation of the complexes of UMB with each aromatic amino acid in a molar ratio of 1：1.The binding constant Kcof UMB with Trp,Tyr and Phe is 2.993×106,7.858×104 and 1.186×103 L.mol-1（298.15K）and 2.702×104,1.063×105 and 8.352×103 L.mol-1（310.15K）,respectively.The thermodynamic parameters indicate that UMB has a strong interaction with the three aromatic amino acids.Hydrogen bond and Van der Waals force may play a major role in the reaction of UMB with Trp,whereas hydrophobic interaction should be responsible for the binding of UMB with Tyr and Phe.In addition,the dipole-dipole interaction may be another factor in the reactions between UMB and the three aromatic amino acids.