Second harmonic generation from tryptophan-rich short peptides: W(n)K(m) and gramicidin A

We report the first hyperpolarizability of a series of tryptophan-rich short peptides with the respective sequence KWK, KWWK, KWWWK, KWWKWWK, where W and K stand for tryptophan and lysine. The measurements were performed with the technique of hyper-Rayleigh scattering in the bulk of an aqueous Tris...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2014-09, Vol.118 (35), p.10413-10418
Main Authors: Duboisset, J, Matar, G, Besson, F, Ficheux, D, Benichou, E, Russier-Antoine, I, Jonin, Ch, Brevet, P F
Format: Article
Language:English
Subjects:
Biochemistry
Biochemistry, Molecular Biology
Gramicidin - chemistry
Hydrogen-Ion Concentration
Ipodate - chemistry
Life Sciences
Lysine - chemistry
Models, Molecular
Nonlinear Dynamics
Peptides - chemistry
Peptides - genetics
Scattering, Radiation
Solutions
Solvents - chemistry
Spectrometry, Fluorescence
Trifluoroethanol - chemistry
Tromethamine - chemistry
Tryptophan - chemistry
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Summary:We report the first hyperpolarizability of a series of tryptophan-rich short peptides with the respective sequence KWK, KWWK, KWWWK, KWWKWWK, where W and K stand for tryptophan and lysine. The measurements were performed with the technique of hyper-Rayleigh scattering in the bulk of an aqueous Tris buffer solution at a pH of 8.5 and a salt concentration of 150 mM at the non-resonant fundamental wavelength of 784 nm. The first hyperpolarizability of the different peptides follows a simple additive model scaling with the number of tryptophan residues contained in the peptide. However, it appears that the first hyperpolarizability response of a single tryptophan residue in the peptide strongly differs from that of an isolated tryptophan. Hence, it is therefore demonstrated that the local environment of the tryptophan residues within the peptide strongly influences its nonlinear optical response. A comparison with the first hyperpolarizability of the natural peptide gramicidin A measured in trifluoroethanol (TFE) further confirms the key role of the local environment on the first hyperpolarizability of tryptophan residues in peptides.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp506416s