Purification, crystallization and preliminary X-ray diffraction analysis of recombinant human neutrophil-activating peptide 2 (rhNAP-2)

The potent activator and chemoattractant for human neutrophils, neutrophil-activating peptide 2 (NAP-2), has been cloned and expressed in Escherichia coli. The protein has been purified to homogeneity (> 98%) by a series of chromatographic techniques, including reversed phase HPLC. The biological activity of recombinant human NAP-2 (rhNAP-2), characterized by the induction of elastase release from human neutrophils, was found to be comparable to natural NAP-2. rhNAP-2 has been crystallized by the hanging drop vapor diffusion method. The crystals belong to space group P222 with unit cell dimensions of a = 30.8 Å, b = 39.5 Å and c = 95.3 Å. A packing density of 3.8 Å 3/Da with a solvent content of approximately 68% is obtained when one molecule per asymmetric unit is assumed. The crystals were shown to diffract to beyond 2.0 Å on a conventional X-ray source. They are stable to X-rays for several days and are thus suitable for high resolution structure determination.