%0 Journal Article %T Vibrational analysis of amino acids and short peptides in hydrated media. 3. Successive KL repeats induce highly stable beta-strands capable of forming non-H-bonded aggregates. %+ Laboratoire de Biophysique Moléculaire Cellulaire et Tissulaire (BIOMOCETI) %+ Chimie Organique %A Guiffo-Soh, Guy %A Hernández, Belén %A Coïc, Yves-Marie %A Boukhalfa-Heniche, Fatima-Zohra %A Fadda, Giulia %A Ghomi, Mahmoud %< avec comité de lecture %@ 1520-6106 %J Journal of Physical Chemistry B %I American Chemical Society %V 112 %N 4 %P 1282-9 %8 2008-01-31 %D 2008 %R 10.1021/jp0767967 %M 18177032 %Z Life Sciences [q-bio]/Other [q-bio.OT]Journal articles %X Circular dichroism (CD) and Raman scattering were applied to the aqueous solution of minimalist LK peptides constructed with successive KL repeats leading to the following generic primary sequence: (KL)nK. Three peptides 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 of interesting 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 Raman spectrum allows finding a mixture of conformations in solution, adopting predominantly beta-type structures. This fact proves the utility of Raman spectroscopy to eliminate eventual ambiguity concerning conformational assignments 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 beta-type structure. On the basis of all the observed results on the 15-mer, we can confirm that this peptide may exist as isolated beta-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 beta-strand aggregates could be proposed as stabilized by an interior hydrophobic core and a hydrophilic external face, formed by leucine and lysine side chains, respectively. %G English %L pasteur-00265277 %U https://pasteur.hal.science/pasteur-00265277 %~ PASTEUR %~ UNIV-PARIS13 %~ UPMC %~ CNRS %~ RIIP_PARIS %~ GIP-BE %~ SORBONNE-UNIVERSITE %~ SORBONNE-PARIS-NORD %~ ALLIANCE-SU