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UV resonance Raman investigation of the conformations and lowest energy allowed electronic excited states of tri- and tetraalanine: Charge transfer transitions

Sharma, B and Asher, SA (2010) UV resonance Raman investigation of the conformations and lowest energy allowed electronic excited states of tri- and tetraalanine: Charge transfer transitions. Journal of Physical Chemistry B, 114 (19). 6661 - 6668. ISSN 1520-6106

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Abstract

UV resonance Raman excitation profiles and Raman depolarization ratios were measured for trialanine and tetraalanine between 198 and 210 nm. Excitation within the π → π* electronic transitions of the peptide bond results in UVRR spectra dominated by amide peptide bond vibrations. In addition to the resonance enhancement of the normal amide vibrations, we find enhancement of the symmetric terminal COO- vibration. The Ala3 UVRR AmIII3 band frequencies indicate that poly-proline II and 2.5 1 helix conformations and type II turns are present in solution. We also find that the conformation of the interior peptide bond of Ala4 is predominantly poly-proline-II-like. The Raman excitation profiles of both Ala3 and Ala4 reveal a charge transfer electronic transition at 202 nm, where electron transfer occurs from the terminal nonbonding carboxylate orbital to the adjacent peptide bond π* orbital. Raman depolarization ratio measurements support this assignment. An additional electronic transition is found in Ala4 at 206 nm. © 2010 American Chemical Society.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Sharma, B
Asher, SAasher@pitt.eduASHER
Date: 20 May 2010
Date Type: Publication
Journal or Publication Title: Journal of Physical Chemistry B
Volume: 114
Number: 19
Page Range: 6661 - 6668
DOI or Unique Handle: 10.1021/jp100428n
Schools and Programs: Dietrich School of Arts and Sciences > Chemistry
Refereed: Yes
ISSN: 1520-6106
MeSH Headings: Alanine--chemistry; Electron Transport; Electrons; Peptides--chemistry; Protein Structure, Secondary; Quantum Theory; Spectrum Analysis, Raman; Ultraviolet Rays; Vibration
Other ID: NLM NIHMS199674, NLM PMC2890231
PubMed Central ID: PMC2890231
PubMed ID: 20420366
Date Deposited: 08 Feb 2013 20:56
Last Modified: 22 Jun 2021 13:55
URI: http://d-scholarship.pitt.edu/id/eprint/17247

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