Linked Life Data

15123612

Source:http://linkedlifedata.com/resource/pubmed/id/15123612

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
31
pubmed:dateCreated
2004-7-26
pubmed:abstractText
Using X-band electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopy at liquid helium temperatures, the Cu(II) coordination geometry at the active site of bovine and human copper,zinc-superoxide dismutases (bSOD1 and hSOD1) treated with H(2)O(2) and bicarbonate (HCO(3)(-)) was examined. The time course EPR of wild type human SOD1 (WT hSOD1), W32F hSOD1 mutant (tryptophan 32 substituted with phenylalanine), and bSOD1 treated with H(2)O(2) and HCO(3)(-) shows an initial reduction of active site Cu(II) to Cu(I) followed by its oxidation back to Cu(II) in the presence of H(2)O(2). However, HCO(3)(-) induced a Trp-32-derived radical from WT hSOD1 but not from bSOD1. The mutation of Trp-32 by phenylalanine totally eliminated the Trp-32 radical signal generated from W32F hSOD1 treated with HCO(3)(-) and H(2)O(2). Further characterization of the free radical was performed by UV irradiation of WT hSOD1 and bSOD1 that generated tryptophanyl and tyrosyl radicals. Both proton ((1)H) and nitrogen ((14)N) ENDOR studies of bSOD1 and hSOD1 in the presence of H(2)O(2) revealed a change in the geometry of His-46 (or His-44) and His-48 (or His-46) coordinated to Cu(II) at the active site of WT hSOD1 and bSOD1, respectively. However, in the presence of HCO(3)(-) and H(2)O(2), both (1)H and (14)N ENDOR spectra were almost identical to those derived from native bSOD1. We conclude that HCO(3)(-)-derived oxidant does not alter significantly the Cu(II) active site geometry and histidine coordination to Cu(II) in SOD1 as does H(2)O(2) alone; however, the oxidant derived from HCO(3)(-) (i.e. carbonate anion radical) reacts with surface-associated Trp-32 in hSOD1 to form the corresponding radical.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
30
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
32534-40
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed-meshheading:15123612-Animals, pubmed-meshheading:15123612-Bicarbonates, pubmed-meshheading:15123612-Binding Sites, pubmed-meshheading:15123612-Cattle, pubmed-meshheading:15123612-Copper, pubmed-meshheading:15123612-Electron Spin Resonance Spectroscopy, pubmed-meshheading:15123612-Free Radicals, pubmed-meshheading:15123612-Histidine, pubmed-meshheading:15123612-Humans, pubmed-meshheading:15123612-Hydrogen Peroxide, pubmed-meshheading:15123612-Magnetics, pubmed-meshheading:15123612-Models, Chemical, pubmed-meshheading:15123612-Models, Molecular, pubmed-meshheading:15123612-Models, Statistical, pubmed-meshheading:15123612-Mutation, pubmed-meshheading:15123612-Oxygen, pubmed-meshheading:15123612-Phenylalanine, pubmed-meshheading:15123612-Protons, pubmed-meshheading:15123612-Spectrophotometry, pubmed-meshheading:15123612-Superoxide Dismutase, pubmed-meshheading:15123612-Time Factors, pubmed-meshheading:15123612-Tryptophan, pubmed-meshheading:15123612-Tyrosine, pubmed-meshheading:15123612-Ultraviolet Rays
pubmed:year
2004
pubmed:articleTitle
Direct probing of copper active site and free radical formed during bicarbonate-dependent peroxidase activity of bovine and human copper, zinc-superoxide dismutases. Low-temperature electron paramagnetic resonance and electron nuclear double resonance studies.
pubmed:affiliation
Department of Biophysics and Free Radical Research Center, Medical College of Wisconsin, Milwaukee, 53226, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.