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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
2
|
| pubmed:dateCreated |
1993-2-2
|
| pubmed:abstractText |
The theory of the second-order reversible reaction, A + B<-->A.B, has been extensively discussed. Apparent first-order behavior is observed when, for example, [B] >> [A]. If the reaction exhibits second-order behavior then it is presumed that the concentrations of A and B were initially equal and that they remain equal during the reaction. However, in the case of hydrogen peroxide binding to cytochrome c oxidase, Weng & Baker (1991, Biochemistry 30, 5727-5733) showed that the observed rate was rigorously first order over a broad concentration range of ligand, including the stoichiometric case. It was further shown that kobs increased linearly with [H2O2], precluding the possibility of a rate-limiting, unimolecular pre-step. The current work examines the theoretical rate equation for the bimolecular, reversible reaction when [A] = [B]. Simulations show that this equimolar condition resulted in rigorous exponential binding as kd, the equilibrium dissociation constant for the A.B complex, approached the initial concentration of A (or B). In particular, the second-order simulation was rigorously exponential when [A]o/Kd = 0.5, and showed only minor deviations when the ratio was increased to 25. These results demonstrate that a reversible, bimolecular reaction can appear first order even under second order conditions, without the need for more complicated mechanisms.
|
| pubmed:grant | |
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Sep
|
| pubmed:issn |
0022-5193
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
21
|
| pubmed:volume |
158
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
221-9
|
| pubmed:dateRevised |
2007-11-14
|
| pubmed:meshHeading | |
| pubmed:year |
1992
|
| pubmed:articleTitle |
Apparent first-order behavior under second-order kinetic conditions: a general concept illustrated by the reversible binding of hydrogen peroxide to cytochrome c oxidase.
|
| pubmed:affiliation |
Department of Chemistry, Northern Illinois University, DeKalb 60115.
|
| pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
|