Linked Life Data

9433902

Source:http://linkedlifedata.com/resource/pubmed/id/9433902

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1998-2-19
pubmed:abstractText
The oxidation of myoglobin by H2O2 yields ferrylmyoglobin, which contains two oxidizing equivalents: the oxoferryl complex and an amino acid radical. This study examines the electron paramagnetic resonance (EPR) properties of the resulting amino acid radicals and their inherent kinetic features at [H2O2]/[protein] ratios close to physiological conditions (i.e., < or = 1). The EPR spectrum obtained with continuous flow at room temperature consisted of a composite of three signals: a low intensity signal and two high intensity signals. The former had a g-value of 2.014, contributed 10-15% to the overall spectrum and was ascribed to a peroxyl radical. Of the two high intensity signals, one consisted of a six-line spectrum (g = 2.0048) that contributed approximately 17-19% to the overall signal; hyperfine splitting constants to ring protons permitted to identify this signal as a tyrosyl radical. The other high intensity signal (with similar g-value and underlying that of the tyrosyl radical) was ascribed to an aromatic amino acid upon comparison with the EPR characteristics for radicals in aromatic amino acid-containing peptides. Analysis of these data in connection with amino acid analysis and the EPR spectra obtained under similar conditions with another hemoprotein, hemoglobin, allowed to suggest a mechanism for the formation of the protein radicals in myoglobin. The aromatic amino acid radical was observed to be relatively long lived in close proximity to the heme iron. Hence, it is likely that this is the first site of protein radical; reduction of the oxoferryl complex by Tyr (FeIV=O + Tyr-OH + H+ --> FeIII + H2O + Tyr-O.)--and alternatively by other amino acids--leads to the subsequent formation of other amino acid radicals within an electron-transfer process throughout the protein. This view suggests that the protein radical(s) is highly delocalized within the globin moiety in a dynamic process encompassing electron tunneling through the backbone chain or H-bonds and leading to the formation of secondary radicals.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0891-5849
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
24
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
269-79
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Heme protein radicals: formation, fate, and biological consequences.
pubmed:affiliation
Department of Molecular Pharmacology and Toxicology, School of Pharmacy, University of Southern California, Los Angeles 90033, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.