Purification and characterization of an antimicrobial protein from Gastrodia elata Blume tubers
Purpose: To purify and characterize a novel antimicrobial protein from the Gastrodia elata Blume (Bl.) plant, which has long been used in herbal medicine.
Methods: The procedure for isolation and purification of Gastrodia elata protein (GEP) involved phosphate buffer extraction, ammonium sulfate precipitation, ion-exchange chromatography, and gelfiltration chromatography. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis was employed to detect the apparent molecular mass and determine homogeneity, while paper disc diffusion was used to measure the antibacterial activity of GEP. A hemolytic assay was performed on rabbit red blood cells. The effect of pH, salt concentration, and temperature on the antibacterial activity of GEP was evaluated by minimum inhibitory concentration assay.
Results: GEP was a 14-kDa monomer and displayed antimicrobial activity against Staphylococcus aureus and Candida albicans, with 8.0-mm and 9.4-mm zones of inhibition, respectively, but no antibacterial activity was observed against Escherichia coli. GEP had little hemolytic activity on red blood cells even at a concentrations of up to 200 mg/ml. GEP was thermally stable at temperatures below 70 °C for 30 min, and displayed higher antibacterial activity in the pH range 5.0 to 7.0.
Conclusion: GEP protein is relatively thermostable and possesses antimicrobial activity. The results suggest that GEP protein has potential agricultural and industrial applications, such as in transgenic plants.
Keywords: Antimicrobial protein, Gastrodia elata, Protein characterization