1ezl
From Proteopedia
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'''CRYSTAL STRUCTURE OF THE DISULPHIDE BOND-DEFICIENT AZURIN MUTANT C3A/C26A: HOW IMPORTANT IS THE S-S BOND FOR FOLDING AND STABILITY?''' | '''CRYSTAL STRUCTURE OF THE DISULPHIDE BOND-DEFICIENT AZURIN MUTANT C3A/C26A: HOW IMPORTANT IS THE S-S BOND FOR FOLDING AND STABILITY?''' | ||
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[[Category: Leckner, J.]] | [[Category: Leckner, J.]] | ||
[[Category: Sjolin, L.]] | [[Category: Sjolin, L.]] | ||
| - | [[Category: | + | [[Category: Crystal structure]] |
| - | [[Category: | + | [[Category: Disulphide bond]] |
| - | [[Category: | + | [[Category: Greek key fold]] |
| - | [[Category: | + | [[Category: Mutant]] |
| - | [[Category: | + | [[Category: Protein folding]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:42:39 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 12:42, 2 May 2008
CRYSTAL STRUCTURE OF THE DISULPHIDE BOND-DEFICIENT AZURIN MUTANT C3A/C26A: HOW IMPORTANT IS THE S-S BOND FOR FOLDING AND STABILITY?
Overview
Azurin has a beta-barrel fold comprising eight beta-strands and one alpha helix. A disulfide bond between residues 3 and 26 connects the N-termini of beta strands beta1 and beta3. Three mutant proteins lacking the disulfide bond were constructed, C3A/C26A, C3A/C26I and a putative salt bridge (SB) in the C3A/S25R/C26A/K27R mutant. All three mutants exhibit spectroscopic properties similar to the wild-type protein. Furthermore, the crystal structure of the C3A/C26A mutant was determined at 2.0 A resolution and, in comparison to the wild-type protein, the only differences are found in the immediate proximity of the mutation. The mutants lose the 628 nm charge-transfer band at a temperature 10-22 degrees C lower than the wild-type protein. The folding of the zinc loaded C3A/C26A mutant was studied by guanidine hydrochloride (GdnHCl) induced denaturation monitored both by fluorescence and CD spectroscopy. The midpoint in the folding equilibrium, at 1.3 M GdnHCl, was observed using both CD and fluorescence spectroscopy. The free energy of folding determined from CD is -24.9 kJ.mol-1, a destabilization of approximately 20 kJ.mol-1 compared to the wild-type Zn2+-protein carrying an intact disulfide bond, indicating that the disulfide bond is important for giving azurin its stable structure. The C3A/C26I mutant is more stable and the SB mutant is less stable than C3A/C26A, both in terms of folding energy and thermal denaturation. The folding intermediate of the wild-type Zn2+-azurin is not observed for the disulfide-deficient C3A/C26A mutant. The rate of unfolding for the C3A/C26A mutant is similar to that of the wild-type protein, suggesting that the site of the mutation is not involved in an early unfolding reaction.
About this Structure
1EZL is a Single protein structure of sequence from Pseudomonas aeruginosa. Full crystallographic information is available from OCA.
Reference
Crystal structure of the disulfide bond-deficient azurin mutant C3A/C26A: how important is the S-S bond for folding and stability?, Bonander N, Leckner J, Guo H, Karlsson BG, Sjolin L, Eur J Biochem. 2000 Jul;267(14):4511-9. PMID:10880975 Page seeded by OCA on Fri May 2 15:42:39 2008
