title: An antifungal peptide from Fagopyrum tataricum seeds.
abstract: A major trypsin inhibitor was isolated and characterized from the seeds of the tartary buckwheat (Fagopyrum tataricum) (FtTI) by ammonium sulfate precipitation, ion exchange chromatography and centrifugal ultrafiltration. SDS-PAGE analysis under reducing condition showed that FtTI is a single polypeptide chain with a molecular mass of approximately 14kDa. The complete amino acid sequence of FtTI was established by automatic Edman degradation and mass spectrometry. It was found that the trypsin inhibitor molecule consists of 86 amino acid residues containing two disulfide bonds which connect Cys(8) to Cys(65) and Cys(49) to Cys(58). The active site of the inhibitor was found to contain an Asp(66)-Arg(67) bond. MALDI-TOF analysis showed that FtTI has two isoforms (Mr: 11.487 and 13.838kDa). Dixon plots revealed a competitive inhibition of trypsin with inhibition constants (Ki) of 1.6nM. Analysis of the amino acid sequence suggests that FtTI is a member of the protease inhibitor I family. What is more, FtTI exhibited strong inhibitory activity against phytopathogenic fungi.
authors: College of Life Science, Sichuan Agriculture University, Yaan 625014, Sichuan, People's Republic of China.
authors: Jing-Jun
authors: JJ
authors: Ruan
authors: Hui
authors: H
authors: Chen
authors: Ji-Rong
authors: JR
authors: Shao
authors: Qi
authors: Q
authors: Wu
authors: Xue-Yi
authors: XY
authors: Han
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D002852:Chromatography, Ion Exchange; D004591:Electrophoresis, Polyacrylamide Gel; D019612:Fagopyrum / Q000737:chemistry* / Q000378:metabolism; D005658:Fungi / Q000187:drug effects* / Q000254:growth & development; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D020033:Protein Isoforms / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D012639:Seeds / Q000737:chemistry* / Q000378:metabolism; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D014357:Trypsin / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D014462:Ultrafiltration
chemical_list: D000935:Antifungal Agents; D010940:Plant Proteins; D020033:Protein Isoforms; D014361:Trypsin Inhibitors; D014357:Trypsin