Linked Life Data

9692986

Source:http://linkedlifedata.com/resource/pubmed/id/9692986

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
31
pubmed:dateCreated
1998-8-24
pubmed:abstractText
The positive and negative cooperativity and apparent half-site reactivity of the Co(II)-substituted insulin hexamer are well-described by a three-state allosteric model involving ligand-mediated interconversions between the three states: T3T3' right harpoon over left harpoon T3o R3o right harpoon over left harpoon R3R3' [Bloom, C. R., Heymann, R., Kaarsholm, N. C., and Dunn, M. F. (1997) Biochemistry 36, 12746-12758]. Because of the low affinity of the T state for ligands, this model is defined by four parameters: LoA and LoB, the allosteric constants for the T3T3' to T3o R3o and the T3o R3o to R3R3' transitions, respectively, and the two dissociation constants for ligand binding to T3o R3o and to R3R3'. The d-d electronic transitions of the Co(II)-substituted hexamer give optical signatures of the T to R transition which can be quantified, but the "spectroscopically silent" character of Zn(II) has made previous attempts to describe the Zn(II) species difficult. This work shows that the T to R state conformational transitions of the Zn(II) hexamer can be easily quantified using the chromophore 4-hydroxy-3-nitrobenzoate (4H3N). When the chromophore is bound to the HisB10 sites of the R state, the absorption spectrum of 4H3N is red-shifted, exhibiting strong absorbance and CD signals, whereas 4H3N does not bind to the T state. Hence, 4H3N can be employed as a sensitive indicator of conformation under conditions that do not significantly disturb the T to R state equilibrium. Using 4H3N as an indicator, these studies show that both LoA and LoB are made less favorable by the substitution of Co(II) for Zn(II); LoA is increased by 10-fold while LoB by 35-fold, whereas the ligand affinities of the phenolic pockets are unchanged.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
37
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10937-44
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Comparison of the allosteric properties of the Co(II)- and Zn(II)-substituted insulin hexamers.
pubmed:affiliation
Department of Biochemistry, University of California, Riverside 92521, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't