Abstract

We study atomic models of the thermodynamics of the structural transition of peptides that form α-helices. The effect of sequence variation on α-helix formation for alanine-rich peptides, Ac-Ala 21 - methyl amide (A21) and Ac-A 5 (AAARA) 3 A-methyl amide (Fs peptide), is investigated by atomic simulation studies of the thermodynamics of the helix-coil transition in explicit water. The simulations show that the guanidinium group in the Arg side chains in the Fs peptide interacts with the carbonyl group four amino acids upstream in the chain and desolvates backbone hydrogen bonds. This desolvation can be directly correlated with a higher probability of hydrogen bond formation. We find that Fs has higher helical content than A21 at all temperatures. A small modification in the amber force field reproduces the experimental helical content and helix-coil transition temperatures for the Fs peptide.

Keywords

Hydrogen bondSide chainChemistryHelix (gastropod)AmidePeptideCrystallographyMolecular dynamicsRandom coilAlaninePeptide bondAlpha helixAmino acidComputational chemistryMoleculeCircular dichroismOrganic chemistryPolymer

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Publication Info

Year
2002
Type
article
Volume
99
Issue
5
Pages
2782-2787
Citations
448
Access
Closed

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Angel E. Garcı́a, Kevin Y. Sanbonmatsu (2002). α-Helical stabilization by side chain shielding of backbone hydrogen bonds. Proceedings of the National Academy of Sciences , 99 (5) , 2782-2787. https://doi.org/10.1073/pnas.042496899

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DOI
10.1073/pnas.042496899