title: Biochemical and Molecular Characterization of a Novel Cu/Zn Superoxide Dismutase from Amaranthus hypochondriacus L.: an Intrinsically Disordered Protein.
abstract: A novel Cu/ZnSOD from Amaranthus hypochondriacus was cloned, expressed, and characterized. Nucleotide sequence analysis showed an open reading frame (ORF) of 456 bp, which was predicted to encode a 15.6-kDa molecular weight protein with a pI of 5.4. Structural analysis showed highly conserved amino acid residues involved in Cu/Zn binding. Recombinant amaranth superoxide dismutase (rAhSOD) displayed more than 50 % of catalytic activity after incubation at 100 °C for 30 min. In silico analysis of Amaranthus hypochondriacus SOD (AhSOD) amino acid sequence for globularity and disorder suggested that this protein is mainly disordered; this was confirmed by circular dichroism, which showed the lack of secondary structure. Intrinsic fluorescence studies showed that rAhSOD undergoes conformational changes in two steps by the presence of Cu/Zn, which indicates the presence of two binding sites displaying different affinities for metals ions. Our results show that AhSOD could be classified as an intrinsically disordered protein (IDP) that is folded when metals are bound and with high thermal stability.
authors.affiliation: División Biología Molecular, IPICyT, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4a. Sección, 78216, San Luis Potosí, SLP, Mexico.
authors.forename: Gabriela M
authors.initials: GM
authors.lastname: Montero-Morán
authors.forename: José G
authors.initials: JG
authors.lastname: Sampedro
authors.forename: Gloria
authors.initials: G
authors.lastname: Saab-Rincón
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Cervantes-González
authors.forename: José Á
authors.initials: JÁ
authors.lastname: Huerta-Ocampo
authors.forename: Antonio
authors.initials: A
authors.lastname: De León-Rodríguez
authors.forename: Ana P
authors.initials: AP
authors.lastname: Barba de la Rosa
mesh_terms: D027721:Amaranthus / Q000201:enzymology*; D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002942:Circular Dichroism; D004795:Enzyme Stability / Q000187:drug effects; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000494:pharmacology; D064267:Intrinsically Disordered Proteins / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D055503:Protein Multimerization / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D012965:Sodium Chloride / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism*; D013696:Temperature
chemical_list: D064267:Intrinsically Disordered Proteins; D008670:Metals; D011994:Recombinant Proteins; D012965:Sodium Chloride; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase