A proteomic analysis of Curcuma comosa Roxb. rhizomes

Abstract

Background: The similarly in plant physiology and the difficulty of plant classification, in some medicinal plant species, especially plants of the Zingiberaceae family, are a major problem for pharmacologists, leading to mistaken use. To overcome this problem, the proteomic base method was used to study protein profiles of the plant model, Curcuma comosa Roxb., which is a member of the Zingiberaceae and has been used in traditional Thai medicine as an anti-inflammatory agent for the treatment of postpartum uterine bleeding.

Results: Due to the complexity of protein extraction from this plant, microscale solution-phase isoelectric focusing (MicroSol-IEF) was used to enrich and improve the separation of Curcuma comosa rhizomes phenol-soluble proteins, prior to resolving and analyzing by two-dimensional polyacrylamide gel electrophoresis and identification by tandem mass spectrometry. The protein patterns showed a high abundance of protein spots in the acidic range, including three lectin proteins. The metabolic and defense enzymes, such as superoxide dismutase (SOD) and ascorbate peroxidase, that are associated with antioxidant activity, were mainly found in the basic region. Furthermore, cysteine protease was found in this plant, as had been previously reported in other Zingiberaceae plants.

Conclusion: This report presents the protein profiles of the ginger plant, Curcuma comosa. Several interesting proteins were identified in this plant that may be used as a protein marker and aid in identifying plants of the Zingiberaceae family.

Figure 1

Two-dimensional (IEF-SDS-PAGE) gel electrophoresis profile of the crude phenol-soluble protein fraction isolated from C. comosa rhizomes and analyzed using a linear IEF strip of (A) pH 3-10 and (B) pH 3.9-5.1. Protein molecular weight markers were co-resolved in the second (SDS-PAGE) dimension on the right hand side, with the sizes indicated in the figure. The gels shown are representative of three such repeats.

Figure 2

Two-dimensional (IEF-SDS-PAGE) gel electrophoresis profiles of the crude phenol-soluble protein fraction isolated from C. comosa rhizomes after separation and enrichment with microscale solution-phase isoelectric focusing (Zoom IEF) at a pH range of (A) 3-5.4 and (B) 5.4-10. The two enriched samples were then resolved in the first dimension using a linear IEF strip of (A) pH 3.9-5.1 and (B) pH 3-10. Protein molecular weight markers were co-resolved in the second (SDS-PAGE) dimension on the right hand side, with the sizes indicated in the figure. The gels shown are representative of three such repeats.

Figure 3

Functional distribution of the 42 putatively identified phenol-soluble proteins (see Table 1) expressed in C. comosa rhizomes. Protein functions are ascribed from that which was annotated in the database to the likely hit (homolog) found by peptide mapping of the tryptic fragments.