Linked Life Data

12568924

Source:http://linkedlifedata.com/resource/pubmed/id/12568924

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4-5
pubmed:dateCreated
2003-2-5
pubmed:abstractText
The effect of copper/zinc metal ion replacement on the folding free energy of wild type (w.t.) and disulfide bridge depleted (C3A/C26A) azurin has been investigated by differential scanning calorimetry (DSC) and fluorescence techniques. The denaturation experiments have shown that, in both cases, the thermal transitions of the zinc derivative of azurins can be depicted in terms of the classical Lumry-Eyring model, N if U-->F, thus resembling the unfolding path of the two copper proteins. The thermally induced transition of Zn azurin, monitored by fluorescence occurs at lower temperature than the DSC scans indicating that a local conformational rearrangement of the Trp microenvironment, takes place before protein denaturation. For Zn C3A/C26A azurin, the two techniques reveal the same transition temperature. Comparison of the thermodynamic data shows that the presence of Zn in the active site stabilises the three-dimensional structure of azurin only when the disulfide bridge is present. Compared to the copper form of the protein, the unfolding temperature of Zn azurin has increased by 4 degrees C, while the unfolding free energy, deltaG, is 31 kJ/mol higher. Both enthalpic and entropic factors contribute to the observed DeltaG increase. However, the copper/zinc replacement has no effect on the unfolding free energy of C3A/C26A azurin. Taking Cu azurin w.t. as the reference state, for both Cu and Zn C3A/C26A azurin the unfolding free energy is decreased by about 28 kJ/mol, indicating that metal substitution is not able to compensate the destabilising effect induced by the disulfide bridge depletion. It is noteworthy that the thermal denaturation of the Zn derivative, which thermodynamically is the most stable form of azurin, is also characterized by the highest value of the activation energy, E(a), as derived from the kinetic stability analysis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0141-8130
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
163-70
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2003
pubmed:articleTitle
The effect of copper/zinc replacement on the folding free energy of wild type and Cys3Ala/Cys26Ala azurin.
pubmed:affiliation
Laboratorio di Biofisica Molecolare, Dipartimento di Fisica e Unità INFM, Università della Calabria, 87036 Rende (CS), Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't