Local folding proclivities in cyclic b -peptide building blocks: assessment of configuration and heteroatom substitution effects by gas phase conformer-selective laser spectroscopy and quantum chemistry - Archive ouverte HAL Access content directly
Journal Articles Chemistry - A European Journal Year : 2015

Local folding proclivities in cyclic b -peptide building blocks: assessment of configuration and heteroatom substitution effects by gas phase conformer-selective laser spectroscopy and quantum chemistry

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Abstract

This work describes the use of conformer-selective laser spectroscopy following supersonic expansion to probe the local folding proclivities of four-membered ring cyclic β-amino acid building blocks. Emphasis is placed on stereochemical effects as well as on the structural changes induced by the replacement of a carbon atom of the cycle by a nitrogen atom. The amide A IR spectra are obtained and interpreted with the help of quantum chemistry structure calculations. Results provide evidence that the building block with a trans-substituted cyclobutane ring has a predilection to form strong C8 hydrogen bonds. Nitrogen-atom substitution in the ring induces the formation of the hydrazino turn, with a related but distinct hydrogen-bonding network: the structure is best viewed as a bifurcated C8/C5 bond with the N heteroatom lone electron pair playing a significant acceptor role, which supports recent observations on the hydrazino turn structure in solution. Surprisingly, this study shows that the cis-substituted cyclobutane ring derivative also gives rise predominantly to a C8 hydrogen bond, although weaker than in the two former cases, a feature that is not often encountered for this building block.

Dates and versions

cea-01273006 , version 1 (11-02-2016)

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Mohammad Alauddin, Eric Gloaguen, Valérie Brenner, Benjamin Tardivel, Michel Mons, et al.. Local folding proclivities in cyclic b -peptide building blocks: assessment of configuration and heteroatom substitution effects by gas phase conformer-selective laser spectroscopy and quantum chemistry . Chemistry - A European Journal, 2015, 21 (46), pp.16479-16493 ⟨10.1002/chem.201501794⟩. ⟨cea-01273006⟩
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