中药成分七叶内酯-BSA-金属离子的相互作用

以荧光光谱、紫外光谱技术研究了传统中药(秦皮)有效成分七叶内酯与BSA在金属离子Cu2 、Ni2 、Zn2 和Co2 分别共存时的相互作用。发现七叶内酯与BSA的表观结合常数KA、七叶内酯对BSA内源荧光的猝灭常数KP增大,按KA和KP数值改变程度,四种金属离子的排序与Irving-William s稳定性序列部分相符:Co2 >Cu2 >N i2 >Zn2 ,但结合位点数n、结合空间距离r和分子间作用力类型基本未变。推测金属离子可能在七叶内酯与BSA之间以“离子架桥”方式直接参与七叶内酯-BSA的结合过程。

Interaction of active component of traditional chinese medicine esculetin-bovine serum albumin-metal lons

The effect of four metal ions Cu2 ,Ni2 ,Zn2 and Co2 on the interaction between bovine serum albumin(BSA) and esculetin extracted from a Traditional Chinese Medicine fraxinus chinensis bark,was investigated by means of UV and fluorescence spectroscopy.The four metal ions make the quenching efficacy of esculetin to BSA and the apparent association constant KA is higher than that in the absence of these metal ions.The sequence of metal ions,arranged in the order of KA and/or K Pnumerical value,is Co2 >Cu2 >Ni2 >Zn2 ,which is partly accords with Irving-Williams stability series.However,the number of binding sites(n) of esculetin on BSA,the spatial binding distance(r) between esculetin and BSA,and the main type of intermolecular action force are not changed evidently.It is conjectured that metal ions function as bridge ions,joining together esculetin and BSA simultaneously,and participate directly in esculetin-BSA binding process.