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Updated: Jun 13, 2026

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Substituent-Dependent Turn Switching in RGGY Peptidomimetics Containing Alkene Dipeptide Isosteres.

Sayuri Takeo¹, Junko Fujimoto², Kohei Sato^2,3,4

¹Graduate School of Medical Photonics, Shizuoka University, 3-5-1 Johoku, Hamamatsu, Shizuoka 432-8011, Japan.

The Journal of Organic Chemistry

|June 12, 2026

Summary

Alkene dipeptide isosteres (ADIs) are peptide bond mimics. Modifying ADI substituents, like methyl or chloroalkene, alters peptide turn geometry, showing ADIs control peptide structure.

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An Efficient Method for the Synthesis of Peptoids with Mixed Lysine-type/Arginine-type Monomers and Evaluation of Their Anti-leishmanial Activity

An Efficient Method for the Synthesis of Peptoids with Mixed Lysine-type/Arginine-type Monomers and Evaluation of Their Anti-leishmanial Activity

Published on: November 2, 2016

Area of Science:

Medicinal Chemistry
Organic Chemistry
Biochemistry

Background:

Peptide conformation is crucial for biological function.
Alkene dipeptide isosteres (ADIs) serve as stable amide bond surrogates.
Understanding substituent effects on ADI conformation is key for peptide design.

Purpose of the Study:

To investigate how alkene substituents influence the conformational preferences of dipeptide isosteres.
To design and synthesize Arg-Gly-Gly-Tyr peptidomimetics with methylalkene or chloroalkene isosteres.
To analyze the solution structures and conformational outcomes of these modified peptides.

Main Methods:

Synthesis of peptidomimetics incorporating methylalkene and chloroalkene dipeptide isosteres.
Nuclear Magnetic Resonance (NMR) spectroscopy, including NOESY experiments.
Amide temperature-coefficient measurements to assess hydrogen bonding and conformation.

Main Results:

The methylalkene-type ADI adopted a conformation resembling a gamma (γ)-turn.
The chloroalkene-type ADI exhibited a distinct folded geometry, approaching alpha (α)-/epsilon (ε)-turn structures.
Subtle changes in alkene substituents induced significant switching of preferred peptide turn geometries.

Conclusions:

Alkene substituent identity directly impacts the conformational preferences of dipeptide isosteres.
ADIs offer a versatile platform for backbone editing to precisely control peptide turn geometry.
These findings underscore the potential of ADIs in designing peptides with specific, predictable structures.