Open AccessCloning, expression, purification, crystallization and preliminary X‐ray diffraction studies of a major group 7 allergen, Der f 7, from the dust mite Dermatophagoides farinae
Author(s) -
Tan Kang Wei,
Kumar Sundramurthy,
Chew Fook Tim,
Mok Yu Keung
Publication year - 2011
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s174430911103836x
Subject(s) - orthorhombic crystal system , allergen , polyethylene glycol , chemistry , escherichia coli , crystallography , crystallization , crystal structure , chromatography , biology , biochemistry , allergy , immunology , organic chemistry , gene
Der f 7 is a major group 7 allergen from the dust mite Dermatophagoides farinae that shows 86% sequence identity to the homologous allergen Der p 7 from D. pteronyssinus . Der f 7 was successfully overexpressed in an Escherichia coli expression system and purified to homogeneity using Ni–NTA affinity and size‐exclusion column chromatography. SeMet‐labelled Der f 7 was crystallized by the hanging‐drop vapour‐diffusion method using a reservoir solution consisting of 0.1 M bis‐tris pH 7.4 and 28% polyethylene glycol monomethyl ether 2000 at 293 K. X‐ray diffraction data were collected to 2.24 Å resolution using synchrotron radiation. The crystals belonged to the orthorhombic system, space group P 2 1 2 1 2 1 , with unit‐cell parameters a = 50.19, b = 58.67, c = 123.81 Å. Based on the estimated Matthews coefficient (2.16 Å 3 Da −1 ), two molecules of Der f 7 could be present in the asymmetric unit of the crystal lattice.