What question did this study set out to answer?

To determine how methyl side-chain positions affect the 3-D conformations and isomeric populations of protonated tripeptides containing glycine and alanine.

June 14, 2022The Journal of Physical Chemistry AOpen Access

Conformational Changes Induced by Methyl Side-Chains in Protonated Tripeptides Containing Glycine and Alanine Residues

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Authors

SSSummer L. ShermanUniversity of Wisconsin–Madison KFKaitlyn C. FischerUniversity of Wisconsin–Madison ÉGÉtienne GarandUniversity of Wisconsin–Madison

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Implication

Cryogenic ion spectroscopy reveals sequence-dependent conformational shifts in gas-phase protonated tripeptides, indicating that methyl side-chain electron donation governs hydrogen bonding.

Key Points

To determine how methyl side-chain positions affect the 3-D conformations and isomeric populations of protonated tripeptides containing glycine and alanine.
Examined all eight sequence permutations of gas-phase protonated glycine and alanine tripeptides (Gly-Gly-Gly through Ala-Ala-Ala).
Applied infrared predissociation spectroscopy and conformer-specific IR-IR double-resonance spectroscopy to cryogenically cooled ions.
Assigned individual conformer populations by comparing experimental vibrational spectra with electronic structure predictions.
Identified three primary conformational families characterized by the protonation site and the number of internal hydrogen bonds.
Demonstrated that the structural family distributions shift significantly depending on the exact amino acid sequence permutation.
Showed that the observed structural rearrangements result from electron-donating methyl groups modulating the local proton affinities of amine and carbonyl sites.

Cite This Study

Sherman et al. (2022) studied this question.

synapsesocial.com/papers/6a70d3f4c2d7c3090826fa0f https://doi.org/10.1021/acs.jpca.2c02584

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Implication

Cryogenic ion spectroscopy reveals sequence-dependent conformational shifts in gas-phase protonated tripeptides, indicating that methyl side-chain electron donation governs hydrogen bonding.

Conformational Changes Induced by Methyl Side-Chains in Protonated Tripeptides Containing Glycine and Alanine Residues

Discussion

Member takes

Implication

Key Points

Cite This Study

Conformational Changes Induced by Methyl Side-Chains in Protonated Tripeptides Containing Glycine and Alanine Residues

Discussion

Member takes

Implication

Key Points

Cite This Study

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