Effect of pressure on helix‐coil transition of an alanine‐based peptide: An FTIR study

Imamura, Hiroshi; Kato, Masaru

doi:10.1002/prot.22302

Cited by 52 publications

(55 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The volume decrease upon helix formation observed in TTET experiments is in agreement with FTIR studies on Ala-based peptides, which also observed a stabilization of the helical state (17). Using an equilibrium linear Ising model to analyze the FTIR data yielded a reaction volume of −0.98 ± 0.04 cm 3 /mol per residue, which is larger than the reaction volume of −0.23 cm 3 /mol per residue determined by TTET (Fig.…”

Section: Effect Of Pressure On the Elementary Rate Constants For Helisupporting

confidence: 87%

“…Thus, addition or removal of a helical residue proceeds through a transitory high-energy state with a large volume, possibly due to the presence of unsatisfied hydrogen bonds, although steric effects may also be involved. volume of the helical state compared with the unfolded state (17). Molecular dynamics simulations, in contrast, suggested that the unfolded state of Ala-based peptides has a slightly smaller volume than the helical state (18).…”

Section: Significancementioning

confidence: 88%

See 1 more Smart Citation

Transition state and ground state properties of the helix–coil transition in peptides deduced from high-pressure studies

Neumaier

Büttner

Bachmann

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Volume changes associated with protein folding reactions contain valuable information about the folding mechanism and the nature of the transition state. However, meaningful interpretation of such data requires that overall volume changes be deconvoluted into individual contributions from different structural components. Here we focus on one type of structural element, the α-helix, and measure triplet-triplet energy transfer at high pressure to determine volume changes associated with the helix-coil transition. Our results reveal that the volume of a 21-amino-acid alanine-based peptide shrinks upon helix formation. Thus, helices, in contrast with native proteins, become more stable with increasing pressure, explaining the frequently observed helical structures in pressureunfolded proteins. Both helix folding and unfolding become slower with increasing pressure. per molecule) for removing one residue. Thus, addition or removal of a helical residue proceeds through a transitory high-energy state with a large volume, possibly due to the presence of unsatisfied hydrogen bonds, although steric effects may also contribute.protein stability | helix dynamics | protein dynamics U nderstanding the effect of pressure on protein stability and dynamics provides insight into fundamental principles and mechanisms of protein folding (1). For most proteins, increasing pressure shifts the folding equilibrium toward the unfolded state, which, according to Le Chatelier's principle, shows that the native state has a larger volume than the unfolded state (2-4). The origin of the volume increase upon folding has been discussed controversially for a long time. The major obstacle in the interpretation of volume changes is opposing contributions from different effects. Analysis of high-resolution X-ray structures suggested that formation of intramolecular hydrogen bonds and van der Waals interactions in the native state lead to a decrease in atomic volumes and thus to a decrease in protein volume upon folding (5). Further, water around hydrophobic groups has a larger volume than bulk water, which also leads to a decrease in volume upon burial of hydrophobic groups in the native protein (6). On the other hand, formation of ordered water structures around charged groups (7) and solvation of the peptide backbone decrease the water volume (6), which leads to a volume increase upon folding. Recent experimental results suggested that volume changes associated with transfer of groups from solvent to the protein interior upon folding are small and that the formation of void volumes in native proteins is the major origin of the volume increase upon folding (8).Volume changes associated with the formation of protein folding transition states are only poorly characterized. Highpressure stopped-flow experiments on tendamistat (9) and cold shock protein (10), as well as pressure-jump experiments on coldshock protein (10) and an ankyrin repeat domain (11), revealed that volumes of protein folding transition states are close to the volume of the native...

show abstract

Section: Effect Of Pressure On the Elementary Rate Constants For Helisupporting

confidence: 87%

Section: Significancementioning

confidence: 88%

Transition state and ground state properties of the helix–coil transition in peptides deduced from high-pressure studies

Neumaier

Büttner

Bachmann

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Below we focus on the Zimm-Bragg model, as this has been used to characterize the experimental data. 14,15 In particular, the elongation parameter s corresponds to the equilibrium constant for adding a single helical hydrogen bond.…”

Section: Resultsmentioning

confidence: 99%

“…The same model was fitted to the data for RT ln s(P, T) reported by Imamura et al, based on FTIR measurements. 14 The fits to the raw data are shown in Fig. S2 of the supplementary material.…”

Section: Resultsmentioning

confidence: 99%

“…Recent experimental work on the pressure dependence of the helix-coil equilibrium, using either FTIR spectroscopy 13,14 or triplet state quenching experiments 15 has in fact found the opposite trend to that for protein folding: namely a negative reaction volume for helix formation, resulting in pressure stabilization of helices for all positive pressures. The origin of this effect is not clear, especially considering the small magnitude of the volume change (≈0.2-1.0 cm 3 mol −1 per residue).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Role of solvation in pressure-induced helix stabilization

Best

Miller

Mittal

2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

In contrast to the well-known destabilization of globular proteins by high pressure, recent work has shown that pressure stabilizes the formation of isolated α-helices. However, all simulations to date have obtained a qualitatively opposite result within the experimental pressure range. We show that using a protein force field (Amber03w) parametrized in conjunction with an accurate water model (TIP4P/2005) recovers the correct pressure-dependence and an overall stability diagram for helix formation similar to that from experiment; on the other hand, we confirm that using TIP3P water results in a very weak pressure destabilization of helices. By carefully analyzing the contributing factors, we show that this is not merely a consequence of different peptide conformations sampled using TIP3P. Rather, there is a critical role for the solvent itself in determining the dependence of total system volume (peptide and solvent) on helix content. Helical peptide structures exclude a smaller volume to water, relative to non-helical structures with both the water models, but the total system volume for helical conformations is higher than non-helical conformations with TIP3P water at low to intermediate pressures, in contrast to TIP4P/2005 water. Our results further emphasize the importance of using an accurate water model to study protein folding under conditions away from standard temperature and pressure.

show abstract