Linked Life Data

2606105

Source:http://linkedlifedata.com/resource/pubmed/id/2606105

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1990-2-21
pubmed:abstractText
The kinetics of the reaction of H2O2 with compound II of horseradish peroxidase were studied as a function of pH at 25 degrees C and constant ionic strength of 0.11 M. The reaction of H2O2 with compound II involves the transient formation of ferric peroxidase and superoxide anion as the first step followed by the reaction of the intermediate species with H2O2 to form compound III. Both reactions are also observed with peracetic acid as substrate, though the amplitude of the first step was too small for the rate to be measured. Observation of the first reaction was not possible below pH 8.5 under the conditions of this investigation. It tends to occur faster at lower pH so an increasing fraction is lost in the dead time of the stopped-flow apparatus. The rate constants for the second reaction, leading to compound III formation, are small at all pH values, with a maximum of 20 M-1 s-1 at pH 7.0. Groups on the enzyme intermediate species with pKa values of 4.2 and 9.1 appear to be involved in this reaction. Compound III formation is accompanied by oxidation of aromatic amino acid groups on the protein. The compound III formed from horseradish peroxidase compound II and hydrogen peroxide has bands with molar absorption coefficients in excellent agreement with those obtained by flash photolysis of aerated carbonmonoxyperoxidase [Wittenberg, J. B., Noble, R. W., Wittenberg, B. A., Antonini, E., Brunori, M. and Wyman, J. (1967) J. Biol. Chem. 242, 626-634]. Attempts to use m-chloroperbenzoic acid as oxidant resulted in the destruction of compound II.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
22
pubmed:volume
186
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
571-6
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Kinetics of the reaction of compound II of horseradish peroxidase with hydrogen peroxide to form compound III.
pubmed:affiliation
Department of Chemistry, University of Ilorin, Nigeria.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't