1oal
From Proteopedia
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'''ACTIVE SITE COPPER AND ZINC IONS MODULATE THE QUATERNARY STRUCTURE OF PROKARYOTIC CU,ZN SUPEROXIDE DISMUTASE''' | '''ACTIVE SITE COPPER AND ZINC IONS MODULATE THE QUATERNARY STRUCTURE OF PROKARYOTIC CU,ZN SUPEROXIDE DISMUTASE''' | ||
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[[Category: Rocca, B M.D.]] | [[Category: Rocca, B M.D.]] | ||
[[Category: Strambini, G.]] | [[Category: Strambini, G.]] | ||
- | [[Category: | + | [[Category: Oxidoreductase]] |
- | [[Category: | + | [[Category: Prokaryotic cu]] |
- | [[Category: | + | [[Category: Protein electrostatic]] |
- | [[Category: | + | [[Category: Protein-subunit interaction recognition]] |
- | [[Category: | + | [[Category: Zn superoxide dismutase]] |
- | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:35:56 2008'' | |
- | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + |
Revision as of 00:35, 3 May 2008
ACTIVE SITE COPPER AND ZINC IONS MODULATE THE QUATERNARY STRUCTURE OF PROKARYOTIC CU,ZN SUPEROXIDE DISMUTASE
Overview
The influence of the constitutive metal ions on the equilibrium properties of dimeric Photobacterium leiognathi Cu,Zn superoxide dismutase has been studied for the wild-type and for two mutant protein forms bearing a negative charge in the amino acid clusters at the dimer association interface. Depletion of copper and zinc dissociates the two mutant proteins into monomers, which reassemble toward the dimeric state upon addition of stoichiometric amounts of zinc. Pressure-dependent dissociation is observed for the copper-depleted wild-type and mutated enzymes, as monitored by the fluorescence shift of a unique tryptophan residue located at the subunit association interface. The spectral shift occurs slowly, reaching a plateau after 15-20 minutes, and is fully reversible. The recovery of the original fluorescence properties, after decompression, is fast (less than four minutes), suggesting that the isolated subunit has a relatively stable structure, and excluding the presence of stable intermediates during the dimer-monomer transition. The dimer dissociation process is still incomplete at 6.5 kbar for the copper-depleted wild-type and mutated enzymes, at variance with what is generally observed for oligomeric proteins that dissociate below 3 kbar. Measurement of the degree of dissociation, at two different protein concentrations, allows us to calculate the standard volume variation upon association, Delta V, and the dissociation constant K(d0), at atmospheric pressure, (25 ml/mol and 3 x 10(-7)M, respectively). The holoprotein is fully dimeric even at 6.5 kbar, which allows us to evaluate a lower Delta G degrees limit of 11.5 kcal/mol, corresponding to a dissociation constant K(d0)<10(-9)M.
About this Structure
1OAL is a Single protein structure of sequence from Photobacterium leiognathi. Full crystallographic information is available from OCA.
Reference
Active-site copper and zinc ions modulate the quaternary structure of prokaryotic Cu,Zn superoxide dismutase., Cioni P, Pesce A, Morozzo della Rocca B, Castelli S, Falconi M, Parrilli L, Bolognesi M, Strambini G, Desideri A, J Mol Biol. 2003 Mar 7;326(5):1351-60. PMID:12595249 Page seeded by OCA on Sat May 3 03:35:56 2008
Categories: Photobacterium leiognathi | Single protein | Superoxide dismutase | Bolognesi, M. | Castellifalconiparrilli, L. | Cioni, P. | Desideri, A. | Pesce, A. | Rocca, B M.D. | Strambini, G. | Oxidoreductase | Prokaryotic cu | Protein electrostatic | Protein-subunit interaction recognition | Zn superoxide dismutase