Vibrational Analysis of Amino Acids and Short Peptides in Hydrated Media. 3. Successive KL Repeats Induce Highly Stable 
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- 作者：Guy Guiffo-Soh ; Belé ; n Herná ; ndez ; Yves-Marie Coï ; c ; Fatima-Zohra Boukhalfa-Heniche ; Giulia Fadda ; Mahmoud Ghomi
- 刊名：Journal of Physical Chemistry B
- 出版年：2008
- 出版时间：January 31, 2008
- 年：2008
- 卷：112
- 期：4
- 页码：1282 - 1289
- 全文大小：380K
- 年卷期：v.112,no.4(January 31, 2008)
- ISSN：1520-5207
文摘
Circular dichroism (CD) and Raman scattering were applied to the aqueous solution of minimalist LK peptidesconstructed with successive KL repeats leading to the following generic primary sequence: (KL)nK. Threepeptides of this family, a 3-mer (n = 1), a 9-mer (n = 4), and a 15-mer (n = 7), are analyzed in this report.Raman spectra of the 3-mer (KLK, a random chain) and its labile-hydrogen deuterated species yield a set ofinteresting information for analyzing longer peptides of this series. Although the CD spectrum of the 9-mer(KLKLKLKLK) reveals a signal traditionally assigned to a random structure, the corresponding Ramanspectrum allows finding a mixture of conformations in solution, adopting predominantly 
gifchars/beta2.gif" BORDER=0 ALIGN="middle">-type structures.This fact proves the utility of Raman spectroscopy to eliminate eventual ambiguity concerning conformationalassignments in peptides based only on the use of CD technique. Finally, the 15-mer (KLKLKLKLKLKLKLK)gives rise to CD and Raman spectra clearly assignable to a gifchars/beta2.gif" BORDER=0 ALIGN="middle">-type structure. On the basis of all the observedresults on the 15-mer, we can confirm that this peptide may exist as isolated gifchars/beta2.gif" BORDER=0 ALIGN="middle">-strands at low concentration(sub-micromolar), flat-oriented at the air/water interface, whereas at high concentrations (millimolar), non-H-bonded immersible aggregates might be formed. A hypothetical model for these gifchars/beta2.gif" BORDER=0 ALIGN="middle">-strand aggregates couldbe proposed as stabilized by an interior hydrophobic core and a hydrophilic external face, formed by leucineand lysine side chains, respectively.
gifchars/beta2.gif" BORDER=0 ALIGN="middle">-type structures.This fact proves the utility of Raman spectroscopy to eliminate eventual ambiguity concerning conformationalassignments in peptides based only on the use of CD technique. Finally, the 15-mer (KLKLKLKLKLKLKLK)gives rise to CD and Raman spectra clearly assignable to a gifchars/beta2.gif" BORDER=0 ALIGN="middle">-type structure. On the basis of all the observedresults on the 15-mer, we can confirm that this peptide may exist as isolated gifchars/beta2.gif" BORDER=0 ALIGN="middle">-strands at low concentration(sub-micromolar), flat-oriented at the air/water interface, whereas at high concentrations (millimolar), non-H-bonded immersible aggregates might be formed. A hypothetical model for these gifchars/beta2.gif" BORDER=0 ALIGN="middle">-strand aggregates couldbe proposed as stabilized by an interior hydrophobic core and a hydrophilic external face, formed by leucineand lysine side chains, respectively.