A Preliminary Study Of The Proteome, Peptidome And Glycosylation Of Panax Ginseng

Panax ginseng,as one of the most widely used herbal medicines worldwide,is a precious and ancient medicinal plant.The proteins from ginseng are also of great importance for both nutrition value and the mechanism of secondary metabolites.With the completion of ginseng genome sequencing,the proteome profiling has become available for the functional study of ginseng protein components.In this paper,we mainly identify and analyze the proteins and peptides in ginseng roots and cauline leaves.First of all,using different methods to extract ginseng proteins,through the Liquid chromatography-tandem mass spectrometry(LC-MS/MS)system to optimize the extraction technology of ginseng proteins and analyze the protein components of cauline leaves and roots.Next,protein components were isolated by two-dimensional chromatography and detected by mass spectrometry to analyzing and comparing the proteome functional differences in these ginseng tissues.Then,the endogenous peptides and glycosylated peptides were extracted from the cauline leaves and roots of ginseng respectively,and the extracted samples were compared and analyzed.2732 proteins and 3608 proteins were identified from ginseng root and cauline leaf respectively.Further gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway revealed the distinguish difference between ginseng root and leaf.With the analysis of functional proteins related to ginsenoside and the spatial study of ginsenoside biosynthesis,we interestingly found that the UDPglycosyltransferase and cytochrome P450 expression extensively in cauline leaf,which expressed much more than in root.We suspected that the post glucoside synthesis of ginsenosides might be carried out more on cauline leaf and then transported to the root at withering.We conducted a preliminary study of the glycosylation modification in ginseng samples.The results showed that 23 glycoproteins and 44 glycopeptides were identified,where the peptides were corresponded to 23 kinds of peptide backbones.Then we summarized the N-glycan composition and the corresponding glycopeptide sequences in ginseng samples and discussed the distribution of amino acid residues at glycosylation sites.After that,the molecular functions and the number of identified glycopeptides of precursor proteins were sorted out.By analyzing the peptidome,653 and 970 endogenous peptides corresponding to 219 and 228 proteins were respectively identified in cauline leaf and root samples.The results showed that the molecular weight distribution of endogenous peptides was similar,but the amino acid residues at the splicing site in root and cauline leaf were quite different,which depended on the abundant and diverse proteases in ginseng tissues.In addition,the precursor proteins of endogenous peptides also had huge differences in biological function,which was closely related to the functions of root and cauline leaf tissue in the growth process of ginseng.The systematically proteome and peptidome analysis will provide us comprehensive understanding and guidance in ginseng biological activity research and ginsenoside biosynthesis.