title: Apocrustacyanin C(1) crystals grown in space and on earth using vapour-diffusion geometry: protein structure refinements and electron-density map comparisons.
abstract: Models of apocrustacyanin C(1) were refined against X-ray data recorded on Bending Magnet 14 at the ESRF to resolutions of 1.85 and 2 A from a space-grown and an earth-grown crystal, respectively, both using vapour-diffusion crystal-growth geometry. The space crystals were grown in the APCF on the NASA Space Shuttle. The microgravity crystal growth showed a cyclic nature attributed to Marangoni convection, thus reducing the benefits of the microgravity environment, as reported previously [Chayen et al. (1996), Q. Rev. Biophys. 29, 227-278]. A subsequent mosaicity evaluation, also reported previously, showed only a partial improvement in the space-grown crystals over the earth-grown crystals [Snell et al. (1997), Acta Cryst. D53, 231-239], contrary to the case for lysozyme crystals grown in space with liquid-liquid diffusion, i.e. without any major motion during growth [Snell et al. (1995), Acta Cryst. D52, 1099-1102]. In this paper, apocrustacyanin C(1) electron-density maps from the two refined models are now compared. It is concluded that the electron-density maps of the protein and the bound waters are found to be better overall for the structures of apocrustacyanin C(1) studied from the space-grown crystal compared with those from the earth-grown crystal, even though both crystals were grown using vapour-diffusion crystal-growth geometry. The improved residues are on the surface of the protein, with two involved in or nearby crystal lattice-forming interactions, thus linking an improved crystal-growth mechanism to the molecular level. The structural comparison procedures developed should themselves be valuable for evaluating crystal-growth procedures in the future.
authors.affiliation: Department of Chemistry, University of Manchester, Manchester M13 9PL, England.
authors.forename: Jarjis
authors.initials: J
authors.lastname: Habash
authors.forename: Titus J
authors.initials: TJ
authors.lastname: Boggon
authors.forename: James
authors.initials: J
authors.lastname: Raftery
authors.forename: Naomi E
authors.initials: NE
authors.lastname: Chayen
authors.forename: Peter F
authors.initials: PF
authors.lastname: Zagalsky
authors.forename: John R
authors.initials: JR
authors.lastname: Helliwell
mesh_terms: D002352:Carrier Proteins; D003460:Crystallization / Q000379:methods*; D018360:Crystallography, X-Ray; D015394:Molecular Structure; D011506:Proteins / Q000737:chemistry*; D014893:Weightlessness
chemical_list: D002352:Carrier Proteins; D011506:Proteins; C018494:crustacyanins