Investigation of interactions between cytochrome c and ginsenosides by native mass spectrometry and molecular docking simulations.

Abstract

Ginsenosides are considered to be the main functional components in ginseng and possess various important pharmacological activities. The study of the interactions between ginsenosides and proteins is indispensable for understanding the pharmacological activities of ginsenosides. In this work, the interactions of ginsenosides with cytochrome c (cyt c) were investigated by native mass spectrometry and molecular docking simulations. The interactions of four ginsenosides (Rb1 , Rb3 , Rf, Rg1 ) and cyt c in NH4 OAc solution were investigated by electrospray ionization linear ion trap mass spectrometry (ESI-LTQ-MS). Molecular docking simulations of cyt c complexes were carried out by AutoDock. The native mass spectrometry results showed that the four ginsenosides were directly bound to cyt c, with stoichiometric ratios of 1:1 and 2:1 in NH4 OAc. The order of relative binding abilities of ginsenosides to cyt c obtained by ESI-MS was Rb1 > Rb3 > Rf > Rg1 , which was consistent with the docking results. Moreover, molecular docking simulations also indicated potential binding sites of cyt c and ginsenosides. Hydrogen-bond interaction played a very important role in cyt c binding with ginsenosides. It has been demonstrated that native MS is a useful tool to investigate the interactions of ginsenosides with cyt c. Molecular docking is a good complement to ESI analysis, and can provide information on potential binding sites of cyt c-ginsenoside complexess. This strategy will be helpful to further understand the interactions of proteins and small molecules.