Linked Life Data

1536857

Source:http://linkedlifedata.com/resource/pubmed/id/1536857

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1992-3-30
pubmed:abstractText
The influence of pH on the activation of yeast enolase by Mn2+ was measured by steady-state kinetics. The pH influence on the binding of Mn2+ to apoenolase and the enolase-substrate complex was measured by EPR spectroscopy. At pH values above 6.6, activation by Mn2+ is fit by Michaelis-Menten kinetics, but at higher concentrations of Mn2+, inhibition is observed. Under conditions analogous to the kinetic studies, the enzyme binds two Mn2+ per dimer with a Kd in the micromolar range. In the presence of the substrate 2-phosphoglycerate, three thermodynamically distinct cation binding sites per monomer are detected and the binding constants are determined by a fit to the data. As the pH decreases, the reaction velocity decreases and the cation inhibition becomes minimal. Under these conditions, only two Mn2+ binding sites per monomer are observed; the third site must be the inhibitory site. The velocity and kinetic constants are minimally affected by buffer except at pH 5.8 with PIPES. Under these conditions, the velocity is only about 40% that observed with other buffers and only a single binding site for Mn2+ per monomer is detected in the presence or absence of substrate. A direct role in the catalytic mechanism by the second cation is called to question. The binding constant for Mn2+ at site I is independent of pH over the range from 7.5 to 5.2, and the binding at site II increases only slightly over this same pH range. These results indicate that the cation sites at positions I and II contain ligands that are pH independent over this range.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
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
2165-71
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Influence of pH on the Mn2+ activation of and binding to yeast enolase: a functional study.
pubmed:affiliation
Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.