Linked Life Data

7577984

Source:http://linkedlifedata.com/resource/pubmed/id/7577984

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
42
pubmed:dateCreated
1995-12-14
pubmed:abstractText
Electronic absorption, MCD, and 1H NMR spectroscopy have been used to characterize the structures and linkage relationships of three active site states, LS1, HS, and LS2, of the Trp51Ala variant of yeast cytochrome c peroxidase (CcP) in the Fe(III) state. In addition, the binding of three substrates (styrene, catechol, and guaiacol) to the Fe(III) variant has been studied by 1H NMR spectroscopy, and the paramagnetically shifted resonances of the cyanide adduct of the variant have been assigned. The heme iron is hexacoordinated in all three pH-dependent states of the enzyme. LS1, the dominant acidic species, exhibits electronic and MCD spectra indicative of low-spin, bis-histidine coordination environment for the heme iron. The HS form, which dominates at intermediate pH, exhibits electronic, MCD, and 1H NMR spectra characteristic of high-spin heme Fe(III) with axial histidyl and water ligands. The LS2 species exhibits spectroscopic properties indicative of a bis-histidine, low-spin Fe(III) derivative. The equilibrium constants for interconversion of these forms of the variant enzyme are highly dependent on ionic strength, specific anions, and temperature of the solution, with the HS form stabilized relative to the other forms in the presence of several noncoordinating, anionic species. Aromatic substrates such as styrene, catechol, and guaiacol affect the chemical shifts of the heme substituents of the HS species but not of the LS2 species. Based on these results, a model is proposed that accounts to a large extent for the electrostatic origin of the three forms of the active site of the Trp51Ala variant and the mechanisms by which they are differentially stabilized in solution.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
13895-905
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:7577984-Anions, pubmed-meshheading:7577984-Binding Sites, pubmed-meshheading:7577984-Catechols, pubmed-meshheading:7577984-Circular Dichroism, pubmed-meshheading:7577984-Cyanides, pubmed-meshheading:7577984-Cytochrome-c Peroxidase, pubmed-meshheading:7577984-Electrolytes, pubmed-meshheading:7577984-Ferric Compounds, pubmed-meshheading:7577984-Guaiacol, pubmed-meshheading:7577984-Heme, pubmed-meshheading:7577984-Hydrogen Bonding, pubmed-meshheading:7577984-Hydrogen-Ion Concentration, pubmed-meshheading:7577984-Magnetic Resonance Spectroscopy, pubmed-meshheading:7577984-Molecular Structure, pubmed-meshheading:7577984-Mutagenesis, Site-Directed, pubmed-meshheading:7577984-Saccharomyces cerevisiae, pubmed-meshheading:7577984-Spectrophotometry, pubmed-meshheading:7577984-Styrene, pubmed-meshheading:7577984-Styrenes
pubmed:year
1995
pubmed:articleTitle
pH, electrolyte, and substrate-linked variation in active site structure of the Trp51Ala variant of cytochrome c peroxidase.
pubmed:affiliation
Department of Chemistry, University of Florence, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't