CD and Fourier transform ir spectroscopic studies of peptides. II. Detection of beta-turns in linear peptides.
Comparative CD and Fourier transform ir (FTIR) spectroscopic data on N-Boc protected linear peptides with or without the (Pro-Gly) beta-turn motif (e.g., Boc-Tyr-Pro-Gly-Phe-Leu-OH and Boc-Tyr-Gly-Pro-Phe-Leu-OH) are reported herein. The CD spectra, reflecting both backbone and aromatic contributions, were not found to be characteristic of the presence of beta-turns. In the amide I region of the FTIR spectra, analyzed by self-deconvolution and curve-fitting methods, the beta-turn band showed up between 1639 and 1633 cm-1 in trifluoroethanol (TFE) but only for models containing the (Pro-Gly) core. This band was also present in the spectra in chloroform but absent in dimethylsulfoxide. These findings, in agreement with recent ir data on cyclic models and 3(10)-helical polypeptides and proteins in D2O [see S. J. Prestrelski, D. M. Byler, and M. P. Thompson (1991), International Journal of Peptide and Protein Research, Vol. 37, pp. 508-512; H. H. Mantsch, A. Perczel, M. Hollósi, and G. D. Fasman (1992), FASEB Journal, Vol. 6, p. A341; H. H. Mantsch, A. Perczel, M. Hollósi, and G. Fasman (1992), Biopolymers, Vol. 33, pp. 201-207; S. M. Miick, G. V. Martinez, W. R. Fiori, A. P. Todd, and G. L. Millhauser (1992), Nature, Vol. 359, pp. 653-655], suggest that the amide I band, with a major contribution from the acceptor C = O of the 1<--4 intramolecular H bond of beta-turns, appears near or below 1640 cm-1, rather than above 1660 cm-1.(ABSTRACT TRUNCATED AT 250 WORDS)
Hollósi
M
M
Department of Organic Chemistry, Eötvös University, Budapest, Hungary.
Majer
Z
Z
Rónai
A Z
AZ
Magyar
A
A
Medzihradszky
K
K
Holly
S
S
Perczel
A
A
Fasman
G D
GD
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
D010455:Peptides