The Effect of Aliphatic Alcohols on the Helix-Coil Transition of Poly-l-ornithine and Poly-l-glutamic Acid

Conio, G.; Patrone, Eligio; Brighetti, Sergio

doi:10.1016/s0021-9258(18)63000-5

Cited by 103 publications

(49 citation statements)

References 29 publications

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“…The enthalpy of folding (Δ H ) in both TFE and water is favorable, but increases in TFE ( ). Furthermore, our simulation of AK-17 correctly described a similar effect for entropy ( ), which seems to be a general property of analogous model peptides in the presence of alcohols and fluoro-alcohols in solution. , These thermodynamic relations can discriminate several previously proposed models of TFE action . We observed opposite trends in simulations of HAL-1 peptide.…”

Section: Discussionsupporting

confidence: 71%

“…), which seems to be a general property of analogous model peptides in the presence of alcohols and fluoro-alcohols in solution. 14,16 These thermodynamic relations can discriminate several previously proposed models of TFE action. 17 We observed opposite trends in simulations of HAL-1 peptide.…”

Section: ■ Discussionmentioning

confidence: 97%

“…An alternative view of the proposed mechanisms reveals that one class of the effects anticipates the preferential interaction of TFE with a helix and replacement of water molecules in the vicinity of the macromolecule. This effect could provide a low dielectric environment, increasing the strength of intramolecular hydrogen bonds and decreasing competition for intermolecular hydrogen bonds with water molecules. ,− Additionally, desolvation of a helix should decrease the entropic cost for its formation due to the disruption of a network of water molecules by chaotropic effect. − Another class of effects assumes destabilization of exposed amide groups in the unfolded state responsible for favoring compact states with internal hydrogen bonding patterns. , Finally, some hypotheses emphasize the ability of TFE to form clusters in TFE/water mixtures, which can provide a folding-assisting hydrophobic matrix or acts as nanocrowders …”

Section: Introductionmentioning

confidence: 99%

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Effect of TFE on the Helical Content of AK17 and HAL-1 Peptides: Theoretical Insights into the Mechanism of Helix Stabilization

2016

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Fluorinated alcohols such as 2,2,2-trifluoroethanol (TFE) are among the most frequently used cosolvents in experiment studies of peptides. They have significant effects on secondary structure and a particularly strong promotion of α-helix is induced by TFE. In this study we validated recently proposed force field parameters for TFE in molecular dynamics simulations with two model peptides-alanine-rich AK-17 and antimicrobial peptide halictine-1 (HAL-1). In the case of HAL-1, we characterized the effect of TFE on this peptide experimentally by ECD spectroscopy. Our TFE model in question reproduced the helix-promoting effect of TFE and provided insight into the mechanisms of TFE action on peptides. Our simulations confirmed the preferential interaction of TFE molecules with α-helices, although the TFE molecules accumulate in the vicinity of the peptides in various conformations. Moreover, we observed a significant effect of TFE on the thermodynamics of the helix-coil transition and a change in local conformational preferences in the unfolded (coil) state induced by TFE. In addition, our simulation-based analysis suggests that different mechanisms participate in helix stabilization in both model peptides in water and TFE solution. Our results thus support the picture of complex TFE action on peptides that is further diversified by the identity and intrinsic properties of the peptide.

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Section: Discussionsupporting

confidence: 71%

Section: ■ Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Effect of TFE on the Helical Content of AK17 and HAL-1 Peptides: Theoretical Insights into the Mechanism of Helix Stabilization

2016

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“…They concluded that the structure has six helices, five of which are located in the helical region of the polypeptide chain and the rest is located in the P-sheet region of the native state. Although the efficiency is not the same, similar effects of methanol and TFE are expected on the helix formation (Bianchi et al, 1970;Conio et al, 1970;Herskovits et al, 1970;Thomas & Dill, 1993;Shiraki et al, 1995). Comparison between the CD spectra in methanol (Fig.…”

Section: Structural Characterization Of the Helical Denatured State (H) At High Concentrations Of Methanolmentioning

confidence: 67%

“…Addition of alcohol is known to destabilize the tertiary structure of a protein (Conio et al, 1970;Herskovits et al, 1970;Fink & Painter, 1987;Nakano & Fink, 1990) and to stabilize the helical structure (Nelson & Kallenbach, 1986,1989Lehrman et al, 1990;Segawa et al, 1991;Dyson et al, 1992aDyson et al, , 1992bKippen et al, 1994;Shiraki et al, 1995;Hirota et al, 1997). In the previous study (Kamatari et al, 1996), we investigated methanol-induced conformational transitions of cytochrome c in detail, in which we found that the helical state realized at high methanol concentration has an expanded chain structure (H).…”

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confidence: 89%

The methanol‐induced transition and the expanded helical conformation in hen lysozyme

et al. 1998

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Methanol-induced conformational transitions of hen egg white lysozyme were investigated with a combined use of farand near-UV CD and N M R spectroscopies, ANS binding and small-angle X-ray scattering. Addition of methanol induced no global change in the native conformation itself, but induced a transition from the native state to the denatured state which was highly cooperative, as shown by the coincidence of transition curves monitored by the far-and near-UV CD spectroscopy, by isodichroic points in the far-and near-UV CD spectra and by the concomitant disappearance of individual 'H N M R signals of the native state. The ANS binding experiments could detect no intermediate conformer similar to the molten globule state in the process of the methanol denaturation. However, at high concentration of methanol, e.g., 60% (v/v) methanol/water, a highly helical state (H) was realized. The H state had a helical content much higher than the native state, monitored by far-W CD spectroscopy, and had no specific tertiary structure, monitored both by near-UV CD and N M R spectroscopy. The radius of gyration in the H state, 24.9 A, was significantly larger than that in the native state (15.7 A). The Kratky plot for the H state did not show a clear peak and was quite similar to that for the urea-denatured state, indicating a complete lack of globularity. Thus we conclude that the H state has a considerably expanded, flexible broken rod-like conformation which is clearly distinguishable from the "molten globule" state. The stability of both N and H states depends on pH and methanol concentration. Thus a phase diagram involving N and H was constructed.

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Molecular simulation of the effects of alcohols on peptide structure

Dwyer

1999

Biopolymers

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The Effect of Aliphatic Alcohols on the Helix-Coil Transition of Poly-l-ornithine and Poly-l-glutamic Acid

Cited by 103 publications

References 29 publications

Effect of TFE on the Helical Content of AK17 and HAL-1 Peptides: Theoretical Insights into the Mechanism of Helix Stabilization

Effect of TFE on the Helical Content of AK17 and HAL-1 Peptides: Theoretical Insights into the Mechanism of Helix Stabilization

The methanol‐induced transition and the expanded helical conformation in hen lysozyme

Molecular simulation of the effects of alcohols on peptide structure

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