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Updated: Sep 25, 2025

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center
Published on: September 28, 2022
Methionine epimerization in cyclic peptides
Pramodkumar D Jadhav1, Jianheng Shen1, Peta-Gaye Burnett1
1Department of Plant Sciences, University of Saskatchewan Saskatoon SK S7N 5A8 Canada pramodkumar.jadhav@usask.ca martin.reaney@usask.ca.
Abstract:
Bioactive flax cyclic octa- and nona-peptides containing single methionine (Met) and its oxidized forms were treated under mild alkaline conditions to perform regio-selective epimerization. Cyclic peptide epimerization at the Met α-proton in a single chemical step has not been reported previously. The epimerization rate varies among Met oxidation states and ring size. These d-amino isomers along with the developed Met alkylation strategy will enable an approach to novel chemical functionalization of biomolecules. The amino acid configurations were confirmed by Marfey derivatizations, and cytotoxicity studies show the difference among the isomers. These d-amino analogs can act as a potential biomarker in plant protein processing and biomedical applications.
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