Linked Life Data

19326892

Source:http://linkedlifedata.com/resource/pubmed/id/19326892

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
16
pubmed:dateCreated
2009-4-16
pubmed:abstractText
Conformational properties of a 12-residue tryptophan zipper (trpzip) beta-hairpin peptide (AWAWENGKWAWK-NH(2), a modification of the original trpzip2 sequence) are analyzed under equilibrium conditions using ECD and IR spectra of a series of variants, singly and doubly C(1)-labeled with (13)C on the amide CO. The characteristic features of the (13)CO component of the amide I' IR band and their sensitivity to the local structure of the peptide are used to differentiate stabilities for parts of the hairpin structure. Doubly labeled peptide spectra indicate that the ends of the beta-strands are frayed and that the center part is more stable as would be expected from formation of a stable hydrophobic core consisting of four tryptophan residues, and supported by MD simulations. NMR analyses were used to determine a best fit solution structure that is in close agreement with that of trpzip2, except for a small variation in the turn geometry. The distinct vibrational coupling patterns of the labeled sites based on this structure are also well matched by ab initio DFT-level calculations of their IR spectral patterns. Thermal unfolding of the peptides as studied with CD spectra could be fit with an apparent two-state transition model. ECD senses only the tryptophan interactions (tertiary-like) and their overall environment, as shown by TD-DFT modeling of the Trp-Trp pi-pi ECD. However, variation of the amide I IR spectra of (13)C-isotopomers showed that the thermal unfolding process is not cooperative in terms of the peptide backbone (secondary structure), since the transition temperatures sensed for labeled modes differ from those for the whole peptide. The thermal data also evidence dependence on concentration and pH but these cause little spectral variation. This study illustrates the consequences of multistate conformational change at the residue- or sequence-specific level in a system whose structure is dominated by hydrophobic collapse.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
1520-6106
pubmed:author
pubmed:issnType
Print
pubmed:day
23
pubmed:volume
113
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5661-74
pubmed:meshHeading
pubmed:year
2009
pubmed:articleTitle
Cross-strand coupling and site-specific unfolding thermodynamics of a trpzip beta-hairpin peptide using 13C isotopic labeling and IR spectroscopy.
pubmed:affiliation
Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S.