Fourier transform vibrational circular dichroism as a decisive tool for conformational studies of peptides containing tyrosyl residues

Attila Borics, Richard F. Murphy, Sándor Lovas

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Previous UV-circular dichroism (UV-CD) and NMR studies showed that Ac-AAAAAAAEAAKA-NH2 has an α-helical structure in 50% (v/v) aqueous trifluoroethanol. Replacement of Ala1 to Ala6 with Tyr results in spectra that show an apparent loss of helicity in the same solvent. This apparent loss of helicity could be attributed to the coupling of the tyrosyl side chain chromophore with the backbone amide. However, such electronic coupling does not affect the vibrational CD (VCD) spectra. The VCD spectra of the peptides with tyrosyl residues were identical to that of the peptide containing no Tyr, which shows the same α-helical structure. Because it is now clear that Tyr replacement does not change the backbone conformation of peptides, UV-CD measurements should be complemented by VCD to determine the secondary structure when electronic effects can disturb the UV-CD spectrum of the inherent structure.

Original languageEnglish
Pages (from-to)21-24
Number of pages4
Issue number1
Publication statusPublished - 2003


All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

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