Arcoria PJ, Etzkorn FA. A fluoro-alkene mimic of Gly-
trans-Pro produces a stable collagen triple helix.
Org Biomol Chem 2023;
21:4039-4051. [PMID:
37114339 DOI:
10.1039/d3ob00110e]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
We report the first experimental evidence for a fluoro-alkene amide isostere participating in n→π* donation, which stabilizes the collagen triple helix. Of the three amide positions in canonical collagen-like peptides, Gly-Pro, Pro-Hyp, and Hyp-Gly, triple helix stability stands to benefit from substitution of only the isomerizable 3° Gly-Pro amide bond with a trans-locked fluoro-alkene. A (Z)-fluoro-alkene isostere of Gly-trans-Pro was synthesized, and its effect on the thermostability of a collagen-like peptide triple helix was measured. The mixture of enantiomers, Boc-Gly-Ψ[(Z)CFC]-L/D-Pro-OH, was synthesized in 8 steps with 27% overall yield, and the Fmoc-Gly-Ψ[(Z)CFC]-L/D-Pro-Hyp-OBn diastereomers were separated. The Gly-Ψ[(Z)CFC]-Pro isostere installed in a collagen-like peptide forms a stable triple helix. By CD, the thermal melting (Tm) value of the fluoro-alkene peptide was +42.2 ± 0.4 °C, and the Tm value of the control peptide was +48.4 ± 0.5 °C, a difference in stability of ΔTm -6.2 °C. Deshielding of the fluorine nucleus in the 19F NMR spectra is evidence of a stabilizing n→π* electronic interaction.
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