Open AccessCrystallization and preliminary X‐ray analysis of a novel Kunitz‐type kallikrein inhibitor from Bauhinia bauhinioides
Author(s) -
Navarro Marcos Vicente de A. S.,
Vierira Débora F.,
Nagem Ronaldo A. P.,
De Araújo Ana Paula U.,
Oliva Maria Luiza V.,
Garratt Richard C.
Publication year - 2005
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309105028496
Subject(s) - kallikrein , crystallization , bauhinia , chemistry , traditional medicine , biochemistry , medicine , organic chemistry , enzyme
A Kunitz‐type protease inhibitor (BbKI) found in Bauhinia bauhinioides seeds has been overexpressed in Escherichia coli and crystallized at 293 K using PEG 4000 as the precipitant. X‐ray diffraction data have been collected to 1.87 Å resolution using an in‐house X‐ray generator. The crystals of the recombinant protein (rBbKI) belong to the orthorhombic space group P 2 1 2 1 2 1 , with unit‐cell parameters a = 46.70, b = 64.14, c = 59.24 Å. Calculation of the Matthews coefficient suggests the presence of one monomer of rBbKI in the asymmetric unit, with a corresponding solvent content of 51% ( V M = 2.5 Å 3 Da −1 ). Iodinated crystals were prepared and a derivative data set was also collected at 2.1 Å resolution. Crystals soaked for a few seconds in a cryogenic solution containing 0.5 M NaI were found to be reasonably isomorphous to the native crystals. Furthermore, the presence of iodide anions could be confirmed in the NaI‐derivatized crystal. Data sets from native and derivative crystals are being evaluated for use in crystal structure determination by means of the SIRAS (single isomorphous replacement with anomalous scattering) method.