Abstract
A sequential polypeptide with a repeating unit of [dmaPhe-Glu(OMe)-napAla-Glu(OBzl)] was synthesized [dmaPhe=L-p-dimethylaminophenylalanine (D), napAla=L-l-naph-thylalanine (N), Glu(OMe)=γ-methyl L-glutamate (G), Glu(OBzl)=γ-benzyl L-glutamate (G)]. CD spectrum in HFIP/TMP mixed solvent indicated a right-handed α-helical main chain. The spatial arrangement of the chromophores was predicted from an empirical conformational energy calculation. The interchromophore distance between naphthyl and the nearest dimethylamino-phenyl group was 12 Å. Fluorescence spectrum of the polypeptide consisted of the monomer fluorescences of the D group and a very small amount of the exciplex emission. No electron-transfer quenching was observed. The fluorescence behavior is consistent with the predicted arrangement of the chromophores.
Similar content being viewed by others
Article PDF
References
M. Sisido, Makromol. Chem., Suppl., 14, 131 (1985).
M. Sisido, in “Photophysics of Polymers,” C. E. Hoyle and J. M. Torkelson, Ed., ACS Symposium Series No. 358, 1987, Chapter 26.
M. Sisido, Y. Inai, and Y. Imanishi, Macromolecules, in press.
M. Sisido, S. Egusa, and Y. Imanishi, J. Am. Chem. Soc., 105, 1041 (1983).
M. Sisido, R. Tanaka, Y. Inai, and Y. Imanishi, J. Am. Chem. Soc., 111, 6790 (1989).
M. Sisido and Y. Imanishi, Macromolecules, 19, 2187 (1986).
F. A. Momany, R. F. McGuire, A. W. Burgess, and H. A. Scheraga, J. Phys. Chem., 79, 2361 (1975).
A sequential polypeptide having a repeating unit [dmaPhe-Ala-napAla-Glu(OBzl)] has been synthesized in a preliminary experiment of this study. The Ala unit was replaced by a Glu(OMe) unit in the later experiment described in the text, because of the limited solubility of the former polypeptide.
NAMOD molecular model drawing program was used to draw Figure 2. See, Y. Beppu, Computer & Chem., 13, 101 (1989).
The r0 values were calculated from the absorption and fluorescence spectra and the lifetimes of III and IV, measured in HFIP/TMP (3:97) mixed solvent, according to the Förster’s equation. See, I. B. Berlman, “Energy Transfer Parameters of Aromatic Compounds,” Academic Press, New York, N. Y., 1973.
The intrinsic lifetimes of D and N group was measured for IV and III in TMP. The fluorescence decay curves were well fitted to single-exponential decay functions.
For the energy transfer between two chromophores which are spatially fixed on a molecular frame, the orientation factor κ2=[e1·e2−3(e1·r)×(e2·r)] may deviate from the value for the averaged value for the random relative orientation (2/3). However, since the lowest excited states of D and N groups have a forbidden character, the directions of the fiuorescent and the absorption transition moments are not clearly defined, but are distributed over the aromatic plane depending on the type of vibronic transitions. Under this circumstances, the use of the averaged orientation factor may be the best possible approximation. The qualitative discussion made in the text dose not change by a small change in the orientation factor.
Y. Inai, M. Sisido, and Y. Imanishi, submitted to J. Phys. Chem.
The quantum yield of the N*→D energy transfer for N* group is estimated from the intrinsic lifetime of N group and the rate constant of the energy transfer predicted.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Inai, Y., Sisido, M. & Imanishi, Y. Polypeptide Carrying a Periodic Arrangement of Naphthyl and p-Dimethylaminophenyl Groups. Two Chromophoric Arrays along a Single α-Helical Polypeptide Chain. Polym J 22, 223–232 (1990). https://doi.org/10.1295/polymj.22.223
Issue Date:
DOI: https://doi.org/10.1295/polymj.22.223