Protocol Optimization of Proteomic Analysis of Korean Ginseng (Panax ginseng Meyer)

The benefits of ginseng have been mainly attributed to its triterpenoids, called ginsenosides. Recent genome sequencing of the Panax ginseng has paved the way for in-depth proteomic studies of this medicinal plant. The current study was conducted to deepen the proteomic information on the root proteome of Korean ginseng. Proteomic workflow was optimized by testing two different strategies, characterized by the phenol extraction procedure, the presence or the absence of SDS-PAGE fractionation step, and nano-scale liquid chromatographic tandem mass spectrometry (nLC-MS/MS) analysis. The results highlighted an evident improvement of proteome extraction by the combination of phenol extraction with SDS-PAGE before the nLC-MS/MS analysis. In addition, a dramatic impact of the steaming process (the treatment to produce red ginseng from ginseng) on protein properties was observed. Overall, the analyses of Korean ginseng permitted the characterization of a total of 2412 proteins. A large number of identified proteins belonged to the functional categories of protein and carbon/energy metabolism (22.4% and 14.6%, respectively). The primary and secondary metabolisms are major metabolic pathways, which emerged from the proteomic analysis. In addition, a large number of proteins known to play an important role in response to (a)biotic stresses were also identified. The current proteomic study not only confirmed the previous transcriptomic and proteomic reports but also extended proteomic information, including the main metabolic pathways involved in Korean ginseng.