Linked Life Data

11389584

Source:http://linkedlifedata.com/resource/pubmed/id/11389584

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
2001-6-6
pubmed:abstractText
The changes in the reduction potential of Pseudomonas aeruginosa and Alcaligenes denitrificans azurins following point mutations and residue ionizations were factorized into the enthalpic and entropic contributions through variable temperature direct electrochemistry experiments. The effects on the reduction enthalpy due to changes in the first coordination sphere of the copper ion, as in the Met121Gln and Met121His variants of A. denitrificans azurin, insertion of a net charge and alteration in the solvation properties and electrostatic potential in proximity of the metal site, as in the Met44Lys and His35Leu variants of P. aeruginosa azurin, respectively, and proton uptake/release in wild-type and mutated species could invariably be accounted for on the basis of simple coordination chemistry and/or electrostatic considerations. The concomitant changes in reduction entropy were found in general to contribute to the E degrees ' variation to a lesser extent as compared to the enthalpy changes. However, their effects were by no means negligible and in some instances were found to heavily contribute to (or even become the main determinant of) the observed change in reduction potential. Several lines of evidence indicate that the entropic effects are notably influenced by reduction-induced solvent reorganization effects. In particular, protein reduction tends to be favored on entropic grounds with increasing exposure of the copper site to the solvent. Moreover, enthalpy-entropy compensation phenomena are invariably observed when residue mutation or pH-induced conformational changes modify the solvent accessibility of the metal site or alter the H-bonding network in the hydration shell of the molecule. Therefore, in these cases, caution must be used in making predictions of E degrees ' changes simply based on Coulombic or coordination chemistry arguments.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
40
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6707-12
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2001
pubmed:articleTitle
Enthalpic and entropic contributions to the mutational changes in the reduction potential of azurin.
pubmed:affiliation
Department of Chemistry, University of Modena and Reggio Emilia, Via Campi 183, 41100 Modena, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't