title: Three-dimensional structure of an unusual Kunitz (STI) type trypsin inhibitor from Copaifera langsdorffii.
abstract: The crystallographic structure of a novel trypsin inhibitor (CTI) from Copaifera langsdorffii is reported. The structure was solved by MIRAS procedure and refined to a crystallographic residual of 17.3% (R(free) = 20.3%) at 1.8 A resolution. Two isomorphous derivatives were obtained by quick cryo-soaking approach. CTI is the first structure of a member of Kunitz (STI) family formed by two noncovalently bound polypeptide chains and only one disulfide bridge. A standard Kunitz-type inhibitor has a single polypeptide chain and two disulfide bridges. Structural features granting CTI high inhibitory activity are discussed.
authors.affiliation: Grupo de Cristalografia, Department of Physics and Informatics, Institute of Physics (IFSC), University of Sao Paulo, Avenue Trabalhador Saocarlense, 400, CEP 13560-970, Sao Carlos, SP, Brazil.
authors.forename: Sandra
authors.initials: S
authors.lastname: Krauchenco
authors.forename: Ronaldo A P
authors.initials: RA
authors.lastname: Nagem
authors.forename: José A
authors.initials: JA
authors.lastname: da Silva
authors.forename: Sérgio
authors.initials: S
authors.lastname: Marangoni
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
mesh_terms: D018360:Crystallography, X-Ray; D004220:Disulfides / Q000378:metabolism; D007887:Fabaceae / Q000737:chemistry*; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D014361:Trypsin Inhibitors; D000516:alpha-Amylases / Q000037:antagonists & inhibitors
chemical_list: D004220:Disulfides; D010455:Peptides; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D000516:alpha-Amylases