Linked Life Data

17711300

Source:http://linkedlifedata.com/resource/pubmed/id/17711300

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
2007-9-11
pubmed:abstractText
Transferrins have been extensively studied in order to understand how they reversibly bind and release iron. Human serum transferrin (hTF) is a single polypeptide chain that folds into two lobes (N- and C-lobe); each lobe binds a single ferric ion. Iron release induces a large conformational change in each lobe. At the putative endosomal pH of 5.6, measurement of the increase in intrinsic fluorescence upon iron release from the recombinant N-lobe yields two rate constants: 8.9 min-1 and 1.3 min-1. Direct monitoring of iron release from the N-lobe at pH 5.6 (by the decrease in absorbance at 470 nm) gives a single rate constant of 9.1 min-1, definitively establishing that the faster rate constant in the fluorescent studies is due to iron release. To further elucidate the molecular basis of the intrinsic fluorescence change (and the source of the slower rate constant), we examined the contributions of the three individual tryptophan residues in the N-lobe (Trp8, Trp128, and Trp264). Three double mutants, each containing the single remaining tryptophan residue, were produced. In the iron-bound N-lobe, Trp128 and Trp264 are quenched by iron and account for almost the entire fluorescent signal when iron is released. As for the wild-type N-lobe, the fluorescence increase for each of these mutants is best fit by a double-exponential function indicating two processes. Trp8 is severely quenched under all conditions, making virtually no contribution to the signal. Additionally, a mutant lacking all three Trp residues allows assignment of the fluorescent signal completely to the three tryptophan residues and observation of the presence of one (or more) tyrosinates in the N-lobe that have physiological significance in the uptake of iron.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
46
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10603-11
pubmed:dateRevised
2011-11-17
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Intrinsic fluorescence reports a global conformational change in the N-lobe of human serum transferrin following iron release.
pubmed:affiliation
Department of Biochemistry, University of Vermont, Burlington, Vermont 05405, USA.
pubmed:publicationType
Journal Article, Research Support, N.I.H., Extramural