| Affiliation: | 1. Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy;2. Institute of Chemical Kinetics and Combustion, RAS, Ulitsa Institutskaya 3, Novosibirsk, 630090 Russian Federation
Novosibirsk State University, Ulitsa Pirogova 2, Novosibirsk, 630090 Russian Federation;3. Diamond Light Source Ltd., Harwell Innovation Campus, Chilton, Didcot, Oxfordshire, UK;4. Faculty of Science and Technology, Free University of Bozen-Bolzano, Piazza Università 5, 39100 Bozen-Bolzano, Italy;5. Department of Chemical Science and Technologies, University of Rome Tor Vergata, via della ricerca scientifica 1, 00133 Rome, Italy |
| Abstract: | Trichogin is a natural peptide endowed with antimicrobial and antitumor activity. A member of the peptaibol family, trichogin possesses a C-terminal amino alcohol. In the past, this moiety was substituted for a methyl ester for synthetic purposes and it was observed that this apparently slight modification caused significant changes in the peptide bioactivity. With the aim of understanding the reasons behind such observations, a detailed spectroscopic study on a number of trichogin analogues has been performed. Herein, data obtained from synchrotron radiation circular dichroism, NMR spectroscopy, and fluorescence spectroscopy in organic solvents at cryogenic temperatures are compared with those independently acquired by means of EPR spectroscopy at 80 K. It is unambiguously revealed that the presence of a reversible, temperature-driven, screw-sense interconversion from a right- to left-handed helix is determined by the C-terminal capping moiety. Data demonstrate, for the first time, the key role of a C-terminal methyl ester in promoting peptide screw-sense inversion. |
