eprintid: 17219
rev_number: 22
userid: 1419
dir: disk0/00/01/72/19
datestamp: 2013-02-08 21:07:15
lastmod: 2021-06-12 23:55:16
status_changed: 2013-02-08 21:07:15
type: article
metadata_visibility: show
item_issues_count: 0
eprint_status: archive
creators_name: Mikhonin, AV
creators_name: Asher, SA
creators_name: Bykov, SV
creators_name: Murza, A
creators_email:
creators_email: asher@pitt.edu
creators_email:
creators_email:
creators_id:
creators_id: ASHER
creators_id:
creators_id:
title: UV Raman spatially resolved melting dynamics of isotopically labeled polyalanyl peptide: Slow α-helix melting follows 310-helices and π-bulges premelting
ispublished: pub
divisions: sch_as_chemistry
full_text_status: public
abstract: We used UV resonance Raman (UVRR) to examine the spatial dependence of the T-jump secondary structure relaxation of an isotopically labeled 21-residue mainly Ala peptide, AdP. The AdP penultimate Ala residues were perdeuterated, leaving the central residues hydrogenated, to allow separate monitoring of melting of the middle versus the end peptide bonds. For 5 to 30°C T-jumps, the central peptide bonds show a ∑2-fold slower relaxation time (189 ± 31 ns) than do the exterior peptide bonds (97 ± 15 ns). In contrast, for a 20 to 40°C T-jump, the central peptide bond relaxation appears to be faster (56 ± 6 ns) than that of the penultimate peptide bonds (131 ± 46 ns). We show that, if the data are modeled as a two-state transition, we find that only exterior peptide bonds show anti-Arrhenius folding behavior; the middle peptide bonds show both normal Arrhenius-like folding and unfolding. This anti-Arrhenius behavior results from the involvement of π-bulges/helices and 310-helix states in the melting. The unusual temperature dependence of the (un)folding rates of the interior and exterior peptide bonds is due to the different relative (un)folding rates of 310-helices, α-helices, and π-bulges/helices. Pure α-helix unfolding rates are ∼12-fold slower (∼1 μs) than that of π-bulges and 310-helices. In addition, we also find that the α-helix is most stable at the AdP N-terminus where eight consecutive Ala occur, whereas the three hydrophilic. Arg located in the middle and at the C-terminus destabilize the α-helix in these regions and induce defects such as π-bulges and 310-helices. © 2007 American Chemical Society.
date: 2007-03-29
date_type: published
publication: Journal of Physical Chemistry B
volume: 111
number: 12
pagerange: 3280 - 3292
refereed: TRUE
issn: 1520-6106
id_number: 10.1021/jp0654009
pmid: 17388440
mesh_headings: Algorithms
mesh_headings: Chemistry, Physical
mesh_headings: Kinetics
mesh_headings: Models, Chemical
mesh_headings: Nonlinear Dynamics
mesh_headings: Peptides--chemistry
mesh_headings: Physicochemical Phenomena
mesh_headings: Protein Folding
mesh_headings: Protein Structure, Secondary
mesh_headings: Spectrophotometry, Ultraviolet
mesh_headings: Spectrum Analysis, Raman
mesh_headings: Thermodynamics
chemical_names: Peptides
chemical_names: polyalanine
citation: Mikhonin, AV and Asher, SA and Bykov, SV and Murza, A (2007) UV Raman spatially resolved melting dynamics of isotopically labeled polyalanyl peptide: Slow α-helix melting follows 310-helices and π-bulges premelting. Journal of Physical Chemistry B, 111 (12). 3280 - 3292. ISSN 1520-6106
document_url: http://d-scholarship-dev.library.pitt.edu/17219/1/licence.txt