Linked Life Data

3334855

Source:http://linkedlifedata.com/resource/pubmed/id/3334855

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1988-2-16
pubmed:abstractText
H2O2 was shown to reduce the copper ion of native bovine Cu,Zn superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) (ECu2+) and to oxidize the reduced enzyme (ECu+). The time-course of these processes was monitored by NMR measurement of the longitudinal relaxation rate of the water protons. A steady-state characterized by the same ratio [ECu2+]/[( EC2+] + [ECu+]) was obtained either by starting from the oxidized or the reduced enzyme. The kinetics of these processes appear to be quite complex, since different reactions between H2O2, or its reaction products, and the enzyme-bound copper control the reaction rate. The solution of the differential equations describing the kinetic processes showed that the oxidation and the reduction of the copper ion by H2O2 are first-order with respect to the copper ion itself only when these processes approach the steady-state. The rate constants of the reduction and oxidation reactions were calculated according to these equations and were found to have comparable values which are in the range 5-80 and 5-45 M-1.min-1, respectively, changing the pH from 5.6 to 7 at 0.21 M ionic strength. This result, together with the dependence of the reaction rates on pH and ionic strength, points to HO2- as the reactive species in both processes, and indicates that the electrostatic control of the access of the peroxide to the active site is the rate-determining step of the two redox reactions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
952
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
77-82
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
A kinetic study of the reactions between H2O2 and Cu,Zn superoxide dismutase; evidence for an electrostatic control of the reaction rate.
pubmed:affiliation
Department of Biology, University of Udine, Italy.
pubmed:publicationType
Journal Article