title: Crystallization and preliminary structural results of catalase from human erythrocytes.
abstract: Catalase (hydrogen peroxide:hydrogen peroxide oxidoreductase, E.C. 1. 11.1.6) is present in most aerobic prokaryotic and eukaryotic cells. Despite a large number of studies on catalases, the only mammalian catalase structure available is that from beef liver, in which about 50% of the haem groups are degraded to bile pigments. Three different crystal forms of human erythrocyte catalase were obtained by the hanging-drop vapour-diffusion technique using PEG as precipitant. Monoclinic crystals, with space group P21 and unit-cell parameters a = 102.9, b = 140.0, c = 173.6 A and beta = 103.2 degrees, require NADP(H) in the crystallization solution. Two types of hexagonal packing, with unit-cell parameters of either a = b = 86. 9, c = 255.5 A or a = b = 90.0, c = 521.2 A, were obtained under identical crystallization conditions in the absence of NADP(H). Only one diffraction data set could be collected: this was obtained from the hexagonal crystals with the smaller c axis using synchrotron radiation, with resolution to 2.65 A. A molecular-replacement solution, determined using a modified beef-liver catalase model as a search structure, corresponds to space group P6422 and contains a single subunit in the asymmetric unit, with an estimated solvent volume of about 50%. The packing determined suggests how minor rearrangements might allow the transition between both hexagonal crystal forms and provides an explanation for the anisotropic character of the corresponding diffractions.
authors.affiliation: CID-CSIC, Jordi-Girona 18-26, 08034 -Barcelona, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Maté
authors.forename: M
authors.initials: M
authors.lastname: Ortiz-Lombardía
authors.forename: A
authors.initials: A
authors.lastname: Marina
authors.forename: I
authors.initials: I
authors.lastname: Fita
mesh_terms: D002374:Catalase / Q000097:blood* / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D009249:NADP / Q000097:blood / Q000737:chemistry; D011487:Protein Conformation
chemical_list: D009249:NADP; D002374:Catalase