Linked Life Data

1536852

Source:http://linkedlifedata.com/resource/pubmed/id/1536852

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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1992-3-30
pubmed:abstractText
We have derived analytical expressions for the kinetics of the two mechanisms involved in ligand substitution reactions. These mechanisms are (i) a dissociative mechanism in which the leaving ligand is first dissociated prior to the binding of the incoming ligand and (ii) an associative mechanism where a ternary complex is formed between the incoming ligand and the complex containing the leaving ligand. The equations obtained provide the theoretical basis for differentiating these two mechanisms on the basis of their kinetic patterns of the displacement reactions. Analysis of these equations shows that an associative mechanism can only generate an increasing kinetic pattern for the observed pseudo-first-ordered rate constants as a function of increasing concentration of the incoming ligand and plateaus, in most cases, at a value higher than the off-rate constant of the leaving ligand. However, a dissociative mechanism can generate either an increasing or a decreasing (kapp decreases with increasing concentrations of the incoming ligand) kinetic pattern, depending on the magnitudes of the individual rate constants involved, and, in either case, it will plateau at kapp equal to the koff of the leaving ligand. Therefore, the decreasing kinetic pattern is a hallmark for a dissociative mechanism. This general method was used to settle the dispute of whether NADH is transferred directly via the enzyme-enzyme complex between glycerol-3-phosphate dehydrogenase (GPDH; EC 1.1.1.8) and L-lactate dehydrogenase (LDH; EC 1.1.1.27).(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
31
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2123-8
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Kinetic method for differentiating mechanisms for ligand exchange reactions: application to test for substrate channeling in glycolysis.
pubmed:affiliation
Laboratory of Biochemistry, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
pubmed:publicationType
Journal Article