Purification And Characterization Of An Antimicrobial Protein From Seeds Of Ginkgo Biloba L.

Plants need to obtain the full spectrum of nutrients from the environment where are extremely rich in microorganisms during the growth of plant,but infection remains a rare event.Plants form respective antimicrobial path-way during the long-term development,for example, plants was induced to produce many class of antimicrobial substance including secondary metabolites and protein,and antimicrobial protein of them play the important role of protection against infection.We find that Ginkgo biloba has the ability of anti-disease strong.So,the targets of the experiment are purifying an antimicrobial protein from seeds of ginkgo biloba L.and analysing it's qulities aimed at establishing basis for cloning it's gene and studying the antimicrobial mechanism.Using the seeds of ginkgo biloba as experiment material, an antimicrobial protein was obtained using PBS extraction buffer,40%-80%ammonium sulfate precipitation,ion exchange chromatography on CM-52,and then gel filtration on Sephadex G-50,and analysing it's qualities of molecular weightasoelectric point(PI),amino acid composition, antimicrobial activity and hot stability. The following results was obtained:1. The yield of the antimicrobial protein is 4.4mg from 150g ginkgo biloba seeds.In SDS-PAGE the protein appears as a single band with a molecular weight is 13000Da.2. In IEF-PAGE the protein appears as a single band with the isoelectric point is 9.5 and it is a basic protein.3. Amino acid composition analysis of the protein suggests this protein especially enriches Ala and Arg , but lacks of Cys. The basic amino acids occupy 22% is accordance with high isoelectric point of the protein in IEF-PAGE, amino acid residues amount to 101.4. The protein exerted potent antifungal activity against a variety of fungi, including Fusarium oxysporum, Colletotrichum orbiculare and Gaeumannomyces graminis ,the protein also exhibited a moderate antibacterial action against staphylococcus aureus and Escherichia Coll.5.The protein has higher hot stability, and it shows strong antifungal activity against Fusarium oxysporum when heating of the protein at 90 ℃ for 30 minutes.