Qu Chenling, Yang Liming, Yu Songcheng, Wang Song, Bai Yuping, Zhang Hanqi
College of Chemistry, Jilin University, Changchun 130012, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2009 Oct 1;74(2):478-83. doi: 10.1016/j.saa.2009.06.048. Epub 2009 Jul 1.
In order to evaluate the essence of the interactions of ginsenosides and proteins which are composed by alpha-amino acids, electrospray ionization mass spectrometry was employed to study the noncovalent interactions between ginsenosides (Rb(2), Rb(3), Re, Rg(1) and Rh(1)) and 18 kinds of alpha-amino acids (Asp, Glu, Asn, Phe, Gln, Thr, Ser, Met, Trp, Val, Gly, Ile, Ala, Leu, Pro, His, Lys and Arg). The 1:1 and 2:1 noncovalent complexes of ginsenosides and amino acids were observed in the mass spectra. The dissociation constants for the noncovalent complexes were directly calculated based on peak intensities of ginsenosides and the noncovalent complexes in the mass spectra. Based on the dissociation constants, it can be concluded that the acidic and the basic amino acids, Asp, Glu, Lys and Arg, bound to ginsenosides more strongly than other amino acids. The experimental results were verified by theoretical calculations of parameters of noncovalent interaction between ginsenoside Re and Arg which served as a representative example. Two kinds of binding forms, "head-tail" ("H-T") and "head-head" ("H-H"), were proposed to explain the interaction between ginsenosides and amino acids. And the interaction in "H-T" form was stronger than that in "H-H" form.
为了评估由α-氨基酸组成的人参皂苷与蛋白质之间相互作用的本质，采用电喷雾电离质谱法研究了人参皂苷（Rb₂、Rb₃、Re、Rg₁和Rh₁）与18种α-氨基酸（天冬氨酸、谷氨酸、天冬酰胺、苯丙氨酸、谷氨酰胺、苏氨酸、丝氨酸、蛋氨酸、色氨酸、缬氨酸、甘氨酸、异亮氨酸、丙氨酸、亮氨酸、脯氨酸、组氨酸、赖氨酸和精氨酸）之间的非共价相互作用。在质谱图中观察到了人参皂苷与氨基酸的1:1和2:1非共价复合物。基于质谱图中人参皂苷和非共价复合物的峰强度直接计算了非共价复合物的解离常数。根据解离常数可以得出结论，酸性和碱性氨基酸，即天冬氨酸、谷氨酸、赖氨酸和精氨酸，与人参皂苷的结合比其他氨基酸更强。以人参皂苷Re与精氨酸之间的非共价相互作用参数的理论计算作为代表性例子对实验结果进行了验证。提出了“头-尾”（“H-T”）和“头-头”（“H-H”）两种结合形式来解释人参皂苷与氨基酸之间的相互作用。并且“头-尾”形式的相互作用比“头-头”形式的更强。
