Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-19312
Bregy, H; Heimgartner, H; Helbing, J (2009). A Time-resolved Spectroscopic Comparison of the Photoisomerization of Small beta-Turn-forming Thioxopeptides. Journal of Physical Chemistry. B, 113(6):1756-1762.
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The monosubstituted thioxopeptide Boe-Ala-Pro-psi(SC-NH)-Aib-Ala-OMe is investigated by time-resolved UV-pump/IR-probe and IR-pump/IR-probe spectroscopy, steady-state FTIR-spectroscopy, and NMR-techniques. The compound has a high propensity to adopt a i --> i + 3 hydrogen-bonded conformation. Time-resolved infrared measurements reveal the opening of this beta-turn structure upon trans --> cis photo isomerization of the thioamide bond. Comparison is made with three protected tripeptides containing the -SC-NH-Aib- moiety with different thio-substituted residues. Very similar photo isomerization dynamics and comparable quantum efficiencies are found. Differences are seen for the thermally activated cis --> trans relaxation in the electronic ground state, where thioxopeptides with larger residues next to the thioamide moiety exhibit subsecond isomerization times. Anisotropy measurements indicate a very rigid Aib-containing core structure for all four thioxopeptides in acetonitrile solution.
|Item Type:||Journal Article, refereed, original work|
|Communities & Collections:||07 Faculty of Science > Institute of Physical Chemistry|
07 Faculty of Science > Institute of Organic Chemistry
|Date:||12 February 2009|
|Deposited On:||24 Jun 2009 15:36|
|Last Modified:||09 Jul 2012 05:49|
|Publisher:||American Chemical Society|
|Funders:||Swiss National Science Foundation (SNF)|
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