title: Crystallization and preliminary x-ray diffraction studies of a psychrophilic iron superoxide dismutase from Pseudoalteromonas haloplanktis.
abstract: The Antarctic eubacterium Pseudoalteromonas haloplanktis (Ph) produces a cold-active iron superoxide dismutase (SOD). PhSOD is a homodimeric enzyme, that displays a high catalytic activity even at low temperature. Using hanging-drop vapour-diffusion technique, PhSOD has been successfully crystallized in two different crystal forms. Both crystal forms are monoclinic with space group P2(1) and diffract to 2.1 A resolution. Form I has unit-cell parameters a=45.49A b=103.63A c=50.37A beta=108.2 degrees and contains a homodimer in the asymmetric unit. Form II has unit-cell parameters a=50.48A b=103.78A c=90.25A beta=103.8 degrees and an asymmetric unit containing two PhSOD homodimers. Structure determination has been achieved using molecular replacement. The crystallographic study of this cold-adapted enzyme could contribute to the understanding of the molecular mechanisms of cold-adaptation and of the high catalytic efficiency at low temperature.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Napoli 'Federico II', Via Cintia, I-80126 Napoli, Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Merlino
authors.forename: Irene
authors.initials: I
authors.lastname: Russo Krauss
authors.forename: Immacolata
authors.initials: I
authors.lastname: Castellano
authors.forename: Emmanuele
authors.initials: E
authors.lastname: De Vendittis
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vergara
authors.forename: Filomena
authors.initials: F
authors.lastname: Sica
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D019281:Dimerization; D031161:Pseudoalteromonas / Q000201:enzymology*; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D013482:Superoxide Dismutase