Linked Life Data

9366266

Source:http://linkedlifedata.com/resource/pubmed/id/9366266

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-12-8
pubmed:abstractText
The unfolding by guanidine hydrochloride (GuHCl) and the refolding on dilution of zinc and apoazurin have been monitored by far-UV circular dichroism (CD). With the native protein, the unfolding was followed by CD and optical absorption in the visible spectral region. With the zinc protein, the reversible unfolding has also been followed by tryptophan fluorescence and NMR. The zinc and Cu2+ metal ions remain associated with the protein in the unfolded state. When the unfolding of the native protein is followed by CD, the initial, reversible transition due to unfolding is followed by a slow change associated with the reduction of Cu2+ by the thiol group of the ligand Cys112. The unfolding of apoazurin displays two CD transitions, which evidence suggests represent different folding domains, the least stable one including the metal-binding site and the other one the rest of the beta-sheet structure. Both occur at a lower GuHCl concentration than the unfolding of the native protein. The CD titrations also demonstrate that zinc azurin has a lower stability than the copper protein. Unfolding of zinc azurin followed by tryptophan fluorescence occurs at a much lower GuHCl concentration than the CD changes, and NMR spectra show that there is no loss of secondary and tertiary structure at this concentration, whereas the CD-detected loss of secondary structure correlates with the NMR changes. Thus, the fluorescence change is ascribed to a small local perturbation of the structure around the single tryptophan residue. The differences in stability of the three forms of azurin are discussed in terms of the rack mechanism. A bound metal ion stabilizes the native fold, and this stabilization is larger for Cu(II) than for Zn(II), reflecting the higher affinity of the protein for Cu(II).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
26
pubmed:volume
1342
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
19-27
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
The effect of the metal ion on the folding energetics of azurin: a comparison of the native, zinc and apoprotein.
pubmed:affiliation
Department of Biochemistry and Biophysics, Göteborg University and Chalmers University of Technology, Sweden.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't