Journal article
The conformation of tetraalanine in water determined by polarized Raman, FT-IR, and VCD spectroscopy
Journal of the American Chemical Society, v 126(9), pp 2768-2776
10 Mar 2004
PMID: 14995194
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The present article reports the conformation of cationic tetraalanine in aqueous solution. The determination of the dihedral angles of the two central amino acid residues was achieved by analyzing the amide I' band profile in the respective polarized visible Raman, Fourier transform-IR, and vibrational circular dichroism (VCD) spectra by means of a novel algorithm which utilizes the excitonic coupling between the amide I modes of nearest neighbor and second nearest peptide groups. It is an extension of a recently developed theory (Schweitzer-Stenner, R. Biophys. J., 2002, 83, 523-532). UV electronic circular dichroism (ECD) spectra of the peptides were used to validate the results of the structure analysis. The analyses yielded the dihedral angles (phi(12), psi(12)) = (-70 degrees, 155 degrees ) and (phi(23), psi(23)) = (-80 degrees, 145 degrees ). The obtained values are very close to the Ramachandran coordinates of the polyproline II helix (PPII). The data suggest that this is the conformation predominantly adopted by the peptide at room temperature. This notion was corroborated by the corresponding electronic circular dichroism spectrum. Tetraalanine exhibits a higher propensity for PPII than trialanine for which a 50:50 mixture of polyproline II and an extended beta-strand-like conformation was obtained from recent spectroscopic studies (Eker et al., J. Am. Chem. Soc. 2002, 124, 14330-14341). The temperature dependence of the CD spectra rule out that any cooperativity is involved in the strand if PPII transition. This led to the conclusion that solvent-peptide interactions give rise to the observed PPII stability. Our result can be utilized to understand why the denaturation of helix-forming peptides generally yields a PPII rather than a heterogeneous random conformation.
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Details
- Title
- The conformation of tetraalanine in water determined by polarized Raman, FT-IR, and VCD spectroscopy
- Creators
- Reinhard Schweitzer-Stenner - Department of Chemistry, Drexel University, 32nd and Chestnut Streets, Philadelphia, Pennsylvania 19104, USA. rschweitzer-stenner@drexel.eduFatma EkerKai GriebenowXiaolin CaoLaurence A Nafie
- Publication Details
- Journal of the American Chemical Society, v 126(9), pp 2768-2776
- Publisher
- American Chemical Society; Washington, DC
- Grant note
- P20 RR16439-01 / NCRR NIH HHS S06 GM008102-3052 / NIGMS NIH HHS
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Chemistry
- Web of Science ID
- WOS:000220038800040
- Scopus ID
- 2-s2.0-1542347945
- Other Identifier
- 991014878253604721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Multidisciplinary