Linked Life Data

3167032

Source:http://linkedlifedata.com/resource/pubmed/id/3167032

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
1988-11-23
pubmed:abstractText
The binding of NAD+ to liver alcohol dehydrogenase was studied by stopped-flow techniques in the pH range from 6.1 to 10.9 at 25 degrees C. Varying the concentrations of NAD+ and a substrate analogue used to trap the enzyme-NAD+ complex gave saturation kinetics. The same maximum rate constants were obtained with or without the trapping agent and by following the reaction with protein fluorescence or absorbance of a ternary complex. The data fit a mechanism with diffusion-controlled association of enzyme and NAD+, followed by an isomerization with a forward rate constant of 500 s-1 at pH 8: E E-NAD+ *E-NAD+. The isomerization may be related to the conformational change determined by X-ray crystallography of free enzyme and enzyme-coenzyme complexes. Overall bimolecular rate constants for NAD+ binding show a bell-shaped pH dependence with apparent pK values at 6.9 and 9.0. Acetimidylation of epsilon-amino groups shifts the upper pK to a value of 11 or higher, suggesting that Lys-228 is responsible for the pK of 9.0. Formation of the enzyme-imidazole complex abolishes the pK value of 6.9, suggesting that a hydrogen-bonded system extending from the zinc-bound water to His-51 is responsible for this pK value. The rates of isomerization of E-NAD+ and of pyrazole binding were maximal at pH below a pK of about 8, which is attributable to the hydrogen-bonded system. Acetimidylation of lysines or displacement of zinc-water with imidazole had little effect on the rate of isomerization of the E-NAD+ complex.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5082-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Mechanism of binding of horse liver alcohol dehydrogenase and nicotinamide adenine dinucleotide.
pubmed:affiliation
Department of Biochemistry, University of Iowa, Iowa City 52242.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.