Crystallization and preliminary X-ray analysis of ginkbilobin-2 from Ginkgo biloba seeds:: a novel antifungal protein with homology to the extracellular domain of plant cysteine-rich receptor-like kinases

The antifungal protein ginkbilobin-2 ( Gnk2) from Ginkgo biloba seeds does not show homology to other pathogenesis-related proteins, but does show homology to the extracellular domain of plant cysteine-rich receptor-like kinases. Native Gnk2 purified from ginkgo nuts and the selenomethionine derivative of recombinant Gnk2 ( SeMet-rGnk2) were crystallized by the sitting-drop vapourdiffusion method using different precipitants. X-ray diffraction data were collected from Gnk2 at 2.38 angstrom resolution and from SeMet-rGnk2 at 2.79 angstrom resolution using a synchrotron-radiation source. The crystals of both proteins belonged to the primitive cubic space group P2(1)3, with unit-cell parameters a = b = c = 143.2 angstrom.