Javascript verkar inte påslaget? - Vissa delar av Lunds universitets webbplats fungerar inte optimalt utan javascript, kontrollera din webbläsares inställningar.
Du är här

The role of Tyr41 and His155 in the functional properties of superoxide dismutase from the Archaeon Sulfolobus solfataricus

  • MA Gogliettino
  • F Tanfani
  • A Scire
  • Thomas Ursby
  • BS Adinolfi
  • T Cacciamani
  • E De Vendittis
Publiceringsår: 2004
Språk: Engelska
Sidor: 2199-2208
Publikation/Tidskrift/Serie: Biochemistry
Volym: 43
Nummer: 8
Dokumenttyp: Artikel i tidskrift
Förlag: The American Chemical Society


We have examined and compared the effects of mutating Y41 and H155 in the iron superoxide dismutase (SOD) from the archaeon Sulfolobus solfataricus (Ss). These two neighboring residues in the active site are known to have crucial functions in structurally related SODs from different sources. The metal analysis indicates a slightly lower iron content after either Y41F or H155Q replacement, without any significant substitution of iron for manganese. The specific activity of SsSOD referred to the iron content is 17-fold reduced in the Y41F mutant, whereas it is less than 2-fold reduced by the H155Q mutation. The noticeable pH dependence of the activity of SsSOD and H155Q-SsSOD, due to the ionization of Y41 (pK 8.4), is lost in Y41F-SsSOD. After H155Q and even more after the Y41F substitution, the archaeal enzyme acquires a moderate sensitivity to sodium azide inhibition. The hydrogen peroxide inactivation of SsSOD is significantly increased after H155Q replacement; however, both mutants are insensitive to the modification of residue 41 by phenylmethanesulfonyl fluoride. Heat inactivation studies showed that the high stability of SsSOD is reduced by the H155Q mutation; hovewer, upon the addition of SDS, a much faster inactivation kinetics is observed both with wild-type and mutant SsSOD forms. The detergent is also required to follow thermal denaturation of the archaeal enzyme by Fourier transform infrared spectroscopy; these studies gave information about the effect of mutations and modification on flexibility and compactness of the protein structure. The crystal structure of Y41F mutant revealed an uninterrupted hydrogen bond network including three solvent molecules connecting the iron-ligating hydroxide ion via H155 with F41 and H37, which is not present in structures of the corresponding mutant SODs from other sources. These data suggest that Y41 and H155 are important for the structural and functional properties of SsSOD; in particular, Y41 seems to be a powerful regulator of the activity of SsSOD, whereas H155 is apparently involved in the organization of the active site of the enzyme.


  • Biochemistry and Molecular Biology


  • ISSN: 0006-2960

Box 117, 221 00 LUND
Telefon 046-222 00 00 (växel)
Telefax 046-222 47 20
lu [at] lu [dot] se

Fakturaadress: Box 188, 221 00 LUND
Organisationsnummer: 202100-3211
Om webbplatsen