Linked Life Data

10785378

Source:http://linkedlifedata.com/resource/pubmed/id/10785378

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
9
pubmed:dateCreated
2000-6-15
pubmed:abstractText
A strategic assessment of the contributions of two active-site hydrogen bonds in the binding of nicotinate to recombinant ferric soybean leghaemoglobin a (rLb) was carried out by mutagenic replacement of the hydrogen-bonding residues (H61A and Y30A variants) and by complementary chemical substitution of the carboxylate functionality on the nicotinate ligand. Dissociation constants, Kd (pH 5.5, mu = 0.10 M, 25.0 +/- 0.1 degrees C), for binding of nicotinate to ferric rLb, H61A and Y30A were 1.4 +/- 0.3 microM, 19 +/- 1 microM and 11 +/- 1 microM, respectively; dissociation constants for binding of nicotinamide were, respectively, 38 +/- 1 mM, 50 +/- 2 mM and 12 +/- 1 mM, and for binding of pyridine were 260 +/- 50 microM, 4.5 +/- 0.5 microM and 66 +/- 8 microM, respectively. Binding of cyanide and azide to the H61A and Y30A variants was unaffected by the mutations. The pH-dependence of nicotinate binding for rLb and Y30A was consistent with a single titration process (pKa values 6.9 +/- 0.1 and 6.7 +/- 0.2, respectively); binding of nicotinate to H61A was independent of pH. Reduction potentials for the rLb and rLb-nicotinate derivatives were 29 +/- 2 mV (pH 5.40, 25.0 degrees C, mu = 0.10 M) and - 65 +/- 2 mV (pH 5.42, 25.0 degrees C, mu = 0.10 M), respectively. The experiments provide a quantitative assessment of the role of individual hydrogen bonds in the binding process, together with a definitive determination of the pKa of His61 and unambiguous evidence that titration of His61 controls binding in the neutral to alkaline region.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2581-7
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Investigation of the haem-nicotinate interaction in leghaemoglobin. Role of hydrogen bonding.
pubmed:affiliation
Department of Chemistry, University of Leicester, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't