title: Crystallization and preliminary X-ray crystallographic analysis of the protease inhibitor ecotin in complex with chymotrypsin.
abstract: Ecotin, a homodimeric protein composed of 142-residue subunits, is a novel protease inhibitor present in the periplasm of Escherichia coli. It shows a broad inhibitory specificity towards a group of serine proteases and binds two molecules of protease to form a tetrameric complex in a distinct chelation mechanism. The ecotin-chymotrypsin complex has been crystallized in the triclinic space group P1 with unit-cell parameters a = 57.29, b = 57.39, c = 79.75 A, alpha = 91.49, beta = 88.63 and gamma = 112.45 degrees. The asymmetric unit contains the whole tetrameric complex, consisting of two molecules of chymotrypsin bound to the ecotin dimer, with a corresponding crystal volume per protein mass (VM) of 2.58 A3 Da-1 and a solvent fraction of 48.9%. The crystals diffract beyond 2.0 A with Cu Kalpha X-rays and are very stable in the X-ray beam. Native X-ray data have been collected from a crystal to approximately 2.0 A Bragg spacing.
authors.affiliation: Department of Molecular Biology and Research Center for Cell Differentiation, Seoul National University, Seoul 151-742, Korea.
authors.forename: C S
authors.initials: CS
authors.lastname: Lee
authors.forename: I S
authors.initials: IS
authors.lastname: Seong
authors.forename: H K
authors.initials: HK
authors.lastname: Song
authors.forename: C H
authors.initials: CH
authors.lastname: Chung
authors.forename: S W
authors.initials: SW
authors.lastname: Suh
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; D011480:Protease Inhibitors / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; C039076:Eco protein, E coli; D029968:Escherichia coli Proteins; D033903:Periplasmic Proteins; D011480:Protease Inhibitors; D002918:Chymotrypsin