Crystallization of human complement component C5.
Human complement component C5 has been crystallized using a low-salt batch technique. The crystals are large hexagonal bi-pyramids often larger than 1.5 mm. Although these crystals were grown in low salt (0.1 M NaCl), they are remarkably stable for at least 2 months at 281 K and they are not dissolved in aqueous buffers containing up to 2 M sodium chloride. The space group is P3121 or P3221, and the cell parameters were determined to be a = 144.9, b = 144.9, c = 243.1 A; alpha = 90 degrees, beta = 90, gamma = 120 degrees. At room temperature and cryo-temperatures the crystals diffract at best to 6 A using rotating-anode X-ray sources. Using synchrotron radiation with cryoprotection using 40%(v/v) PEG 400 the resolution limit can be extended to 3.3 A. In both cases the crystals show significant anisotropy, with relatively weaker reflections at higher resolution in the a*b* plane.
La Jolla Institute for Experimental Medicine, 505 Coast Boulevard S., La Jolla, CA 92037, USA. richard@ljiem.org
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D016880:Anisotropy; D003182:Complement C5 / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects; D003460:Crystallization; D018360:Crystallography, X-Ray; D006801:Humans; D011487:Protein Conformation; D017356:Synchrotrons
D003182:Complement C5