http://www.cnr.it/ontology/cnr/individuo/prodotto/ID14208
Structure and flexibility in cold-adapted iron superoxide dismutases: the case of the enzyme isolated from Pseudoalteromonas haloplanktis (Articolo in rivista)
- Type
- Label
- Structure and flexibility in cold-adapted iron superoxide dismutases: the case of the enzyme isolated from Pseudoalteromonas haloplanktis (Articolo in rivista) (literal)
- Anno
- 2010-01-01T00:00:00+01:00 (literal)
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- A. Merlino; I. Russo Krauss; I. Castellano; E. De Vendittis; B. Rossi; M. Conte; A. Vergara; F. Sica (literal)
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- Rivista
- Note
- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- Istituto di Biostrutture e Bioimmagini (literal)
- Titolo
- Structure and flexibility in cold-adapted iron superoxide dismutases: the case of the enzyme isolated from Pseudoalteromonas haloplanktis (literal)
- Abstract
- Superoxide dismutases (SODs) are metalloenzymes catalysing the dismutation of superoxide anion
radicals into molecular oxygen and hydrogen peroxide. Here, we present the crystal structure of a
cold-adapted Fe-SOD from the Antarctic eubacterium Pseudoalteromonas haloplanktis (PhSOD), and that
of its complex with sodium azide. The structures were compared with those of the corresponding homologues
having a high sequence identity with PhSOD, such as the mesophilic SOD from Escherichia coli
(EcSOD) or Pseudomonas ovalis, and the psychrophilic SOD from Aliivibrio salmonicida (AsSOD). These
enzymes shared a large structural similarity, such as a conserved tertiary structure and arrangement
of the two monomers, an almost identical total number of inter- and intramolecular hydrogen bonds
and salt bridges. However, the two cold-adapted SODs showed an increased flexibility of the active site
residues with respect to their mesophilic homologues. Structural information was combined with a characterisation
of the chemical and thermal stability performed by CD and fluorescence measurements.
Despite of its psychrophilic origin, the denaturation temperature of PhSOD was comparable with that
of the mesophilic EcSOD, whereas AsSOD showed a lower denaturation temperature. On the contrary,
the values of the denaturant concentration at the transition midpoint were in line with the psychrophilic/
mesophilic origin of the proteins.
These data provide additional support to the hypothesis that cold-adapted enzymes achieve efficient
catalysis at low temperature, by increasing the flexibility of their active site; moreover, our results underline
how fine structural modifications can alter enzyme flexibility and/or stability without compromising
the overall structure of typical rigid enzymes, such as SODs. (literal)
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