电喷雾质谱法定量分析细胞色素C-皂苷非共价键复合物

Quantitative Analysis of Noncovalent Complexes between Cytochrome C and Saponins by ESI-MS

以中药皂苷提取物人参皂苷Re、柴胡皂苷A、柴胡皂苷C为配体,采用电喷雾质谱法(ESI-MS)检测其与细胞色素C形成的复合物,用直接计算法得出3种皂苷与细胞色素C形成的1∶1非共价键复合物的解离常数Kd1分别为3.6×10-5mol.L-1、4.1×10-5mol.L-1和2.5×10-5mol.L-1,得到皂苷配体分子与细胞色素C结合能力大小依次为:柴胡皂苷C>人参皂苷Re>柴胡皂苷A。为研究细胞色素C所形成的非共价键复合物的性质和特异性提供了实验依据,也进一步验证了ESI-MS是研究蛋白质非共价键复合物的有效分析手段。

The noncovalent complexes between cytochrome C and ligands,e.g.ginsenoside Re,saikosaponin A,saikosaponin C,are investigated by ESI-MS in this paper.The stability of noncovalent complexes is evaluated by the dissociation constant Kd1 by using the direct calculation method.The order of the three ligands＇bind affinity to cytochrome C is：saikosaponin Cginsenoside Resaikosaponin A.This study provides experimental evidence for the characterization of ligand-bound cytochrome C complexes and also demonstrates that ESI-MS is an effective analytical tool for studying protein noncovalent complexes.