Ahmed, Z and Beta, IA and Mikhonin, AV and Asher, SA
(2005)
UV-resonance Raman thermal unfolding study of Trp-cage shows that it is not a simple two-state miniprotein.
Journal of the American Chemical Society, 127 (31).
10943 - 10950.
ISSN 0002-7863
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Abstract
Trp-cage, a synthetic 20 residue polypeptide, is proposed to be an ultrafast folding synthetic miniprotein which utilizes tertiary contacts to define its native conformation. We utilized UV resonance Raman spectroscopy (UVRS) with 204 and 229 nm excitation to follow its thermal melting. Our results indicate that Trp-cage melting is complex, and it is not a simple two-state process. Using 204 nm excitation we probe the peptide secondary structure and find the Trp-cage's α-helix shows a broad melting curve where on average four α-helical amide bonds melt upon a temperature increase from 4 to 70 °C. Using 229 nm excitation we probe the environment of the Trp side chain and find that its immediate environment becomes more compact as the temperature is increased from 4 to 20 °C; however, further temperature increases lead to exposure of the Trp to water. The χ2 angle of the Trp side chain remains invariant throughout the entire temperature range. Previous kinetic results indicated a single-exponential decay in the 4-70 °C temperature range, suggesting that Trp-cage behaves as a two-state folder. However, this miniprotein does not show clear two-state behavior in our steady-state studies. Rather it shows a continuous distribution of steady-state spectral parameters. Only the α-helix melting curve even hints of a cooperative transition. Possibly, the previous kinetic results monitor only a small region of the Trp-cage which locally appears two-state. This would then argue for spatially decoupled folding even for this small peptide. © 2005 American Chemical Society.
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Details
Item Type: |
Article
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Status: |
Published |
Creators/Authors: |
Creators | Email | Pitt Username | ORCID ![](/images/orcid_id_24x24.png) |
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Ahmed, Z | | | | Beta, IA | | | | Mikhonin, AV | | | | Asher, SA | asher@pitt.edu | ASHER | |
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Date: |
10 August 2005 |
Date Type: |
Publication |
Journal or Publication Title: |
Journal of the American Chemical Society |
Volume: |
127 |
Number: |
31 |
Page Range: |
10943 - 10950 |
DOI or Unique Handle: |
10.1021/ja050664e |
Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
Refereed: |
Yes |
ISSN: |
0002-7863 |
MeSH Headings: |
Amino Acid Sequence; Molecular Sequence Data; Peptides--chemistry; Proline--chemistry; Spectrum Analysis, Raman; Temperature; Ultraviolet Rays |
PubMed ID: |
16076200 |
Date Deposited: |
08 Feb 2013 21:13 |
Last Modified: |
12 Jun 2021 23:55 |
URI: |
http://d-scholarship-dev.library.pitt.edu/id/eprint/17210 |
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