Crystallography Journals Online : IUCR Backfile Archive 1948-2001
Chemistry and Pharmacology
Haem-containing catalases are homotetrameric molecules that degrade hydrogen peroxide. Phylogenetically, the haem-containing catalases can be grouped into three main lines or clades. The crystal structures of seven catalases have been determined, all from clades II and III. In order to obtain a structure of an enzyme from clade I, which includes all plant, algae and some bacterial enzymes, two bacterial catalases, CatF from Pseudomonas syringae and Kat from Listeria seeligeri, have been crystallized by the hanging-drop vapour-diffusion technique, using PEG and ammonium sulfate as precipitants, respectively. Crystals of P. syringae CatF, with a plate-like morphology, belong to the monoclinic space group P21, with unit-cell parameters a = 60.6, b = 153.9, c = 109.2 Å, β = 102.8°. From these crystals a diffraction data set to 1.8 Å resolution with 98% completeness was collected using synchrotron radiation. Crystals of L. seeligeri Kat, with a well developed bipyramidal morphology, belong to space group I222 (or I212121), with unit-cell parameters a = 74.4, b = 121.3, c = 368.5 Å. These crystals diffracted beyond 2.2 Å resolution when using synchrotron radiation, but presented anisotropic diffraction, with the weakest direction perpendicular to the long c axis.
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