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Coca-Hidalgo JJ, Recillas-Mota M, Fernández-Quiroz D, Lizardi-Mendoza J, Peniche-Covas C, Goycoolea FM, Argüelles-Monal WM. Study of the Thermal Phase Transition of Poly( N,N-diethylacrylamide- co- N-ethylacrylamide) Random Copolymers in Aqueous Solution. Polymers (Basel) 2024; 16:1575. [PMID: 38891521 PMCID: PMC11175111 DOI: 10.3390/polym16111575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024] Open
Abstract
N-alkyl-substituted polyacrylamides exhibit a thermal coil-to-globule transition in aqueous solution driven by an increase in hydrophobic interactions with rising temperature. With the aim of understanding the role of N-alkyl substituents in the thermal transition, this study focuses on the molecular interactions underlying the phase transition of poly(N,N-diethylacrylamide-co-N-ethylacrylamide) random copolymers. Poly(N,N-diethylacrylamide) (PDEAm), poly(N-ethylacrylamide) (PNEAm), and their random copolymers were synthesized by free radical polymerization and their chemical structure characterized spectroscopically. It was found that the values of the cloud-point temperature increased with PNEAm content, and particle aggregation processes took place, increasing the negative charge density on their surface. The cloud-point temperature of each copolymer decreased with respect to the theoretical values calculated assuming an absence of interactions. It is attributed to the formation of intra- and interchain hydrogen bonding in aqueous solutions. These interactions favor the formation of more hydrophobic macromolecular segments, thereby promoting the cooperative nature of the transition. These results definitively reveal the dominant mechanism occurring during the phase transition in the aqueous solutions of these copolymers.
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Affiliation(s)
- José Javier Coca-Hidalgo
- Centro de Investigación en Alimentación y Desarrollo, Hermosillo 83304, Mexico; (J.J.C.-H.); (M.R.-M.); (J.L.-M.)
| | - Maricarmen Recillas-Mota
- Centro de Investigación en Alimentación y Desarrollo, Hermosillo 83304, Mexico; (J.J.C.-H.); (M.R.-M.); (J.L.-M.)
| | - Daniel Fernández-Quiroz
- Departamento de Ingeniería Química y Metalurgia, Universidad de Sonora, Hermosillo 83000, Mexico;
| | - Jaime Lizardi-Mendoza
- Centro de Investigación en Alimentación y Desarrollo, Hermosillo 83304, Mexico; (J.J.C.-H.); (M.R.-M.); (J.L.-M.)
| | | | | | - Waldo M. Argüelles-Monal
- Centro de Investigación en Alimentación y Desarrollo, Hermosillo 83304, Mexico; (J.J.C.-H.); (M.R.-M.); (J.L.-M.)
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Tariq N, Xu C, Wang J, Kume T, Macgregor RB. Enhancement of the thermal stability of G-quadruplex structures by urea. Biophys Chem 2023; 299:107043. [PMID: 37285661 DOI: 10.1016/j.bpc.2023.107043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 06/09/2023]
Abstract
The solute urea has been used extensively as a denaturant in protein folding studies; double-stranded nucleic acid structures are also destabilized by urea, but comparatively less than proteins. In previous research, the solute has been shown to strongly destabilize folded G-quadruplex DNA structures. This contribution demonstrates the stabilizing effect of urea on the G-quadruplex formed by the oligodeoxyribonucleotide (ODN), G3T (d[5'-GGGTGGGTGGGTGGG-3']), and related sequences in the presence of sodium or potassium cations. Stabilization is observed up to 7 M urea, which was the highest concentration we investigated. The folded structure of G3T has three G-tetrads and three loops that consist of single thymine residues. ODNs related to G3T, in which the thymine residues in the loop are substituted by adenosine residues, also exhibit enhanced stability in the presence of molar concentrations of urea. The circular dichroism (CD) spectra of these ODNs in the presence of urea are consistent with that of a G-quadruplex. As the urea concentration increases, the spectral intensities of the peaks and troughs change, while their positions change very little. The heat-induced transition from the folded to unfolded state, Tm, was measured by monitoring the change in the UV absorption as a function of temperature. G-quadruplex structures with loops containing single bases exhibited large increases in Tm with increasing urea concentrations. These data imply that the loop region play a significant role in the thermal stability of tetra-helical DNA structures in the presence of the solute urea.
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Affiliation(s)
- Nabeel Tariq
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Christine Xu
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Jingtong Wang
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Takuma Kume
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada
| | - Robert B Macgregor
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Canada.
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Liu B, Yan X, Zhao Z, Wang J, Feng J. Distinctly different solvation behaviors of poly( N, N-diethylacrylamide) gels in water/acetone and water/DMSO mixtures. Phys Chem Chem Phys 2022; 24:23893-23902. [PMID: 36165400 DOI: 10.1039/d2cp02144g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solvation behaviors and intermolecular interactions of a poly(N,N-diethylacrylamide) (PDEA) gel network in water/DMSO and water/acetone mixtures have been investigated by variable-temperature high-resolution 1H MAS NMR. Unlike decreasing volume phase transition temperature (VPTT) of the typical thermosensitive poly(N-isopropylacrylamide) (PNIPAM) gel induced by both acetone and DMSO in a water-rich region, distinct phase transition behaviors are revealed for the PDEA gel. That is, acetone is found to increase the VPTT of PDEA directly in the water-rich region while DMSO is also found to increase the VPTT of PDEA at a very low concentration but then decrease the VPTT as the concentration further increases. The above distinctly different VPTT shifts of PDEA are attributed to the different polymer-cosolvent interactions in water/acetone and water/DMSO systems. DMSO molecules with a strong water affinity are preferentially excluded by the PDEA gel network, and can promote the volume phase transition by favoring the collapse of the PDEA gel network, while acetone molecules preferentially adsorbed on the polymer interact with PDEA via non-specific van der Waals interaction, which favors the swollen state of the PDEA gel.
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Affiliation(s)
- Biaolan Liu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Xiaoshuang Yan
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zhihui Zhao
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China. .,University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jian Wang
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jiwen Feng
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
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Pica A, Graziano G. A Rationalization of the Effect That TMAO, Glycine, and Betaine Exert on the Collapse of Elastin-like Polypeptides. Life (Basel) 2022; 12:life12020140. [PMID: 35207427 PMCID: PMC8876568 DOI: 10.3390/life12020140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 11/16/2022] Open
Abstract
Elastin-like polypeptides (ELPs) are soluble in water at low temperature, but, on increasing the temperature, they undergo a reversible and cooperative, coil-to-globule collapse transition. It has been shown that the addition to water of either trimethylamine N-oxide (TMAO), glycine, or betaine causes a significant decrease of T(collapse) in the case of a specific ELP. Traditional rationalizations of these phenomena do not work in the present case. We show that an alternative approach, grounded in the magnitude of the solvent-excluded volume effect and its temperature dependence (strictly linked to the translational entropy of solvent and co-solute molecules), is able to rationalize the occurrence of ELP collapse in water on raising the temperature, as well as the T(collapse) lowering caused by the addition to water of either TMAO, glycine, or betaine.
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Affiliation(s)
- Andrea Pica
- ALPX, 71 Avenue des Martyrs, 38000 Grenoble, France;
| | - Giuseppe Graziano
- Dipartimento di Scienze e Tecnologie, Università del Sannio, Via Francesco de Sanctis snc, 82100 Benevento, Italy
- Correspondence:
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Heying M, Lam K, Richardson AD, Canepa J, Wilkinson SP. Cavity-based free energy analysis of osmolyte effects on protein denaturation. Phys Chem Chem Phys 2022; 24:5394-5403. [DOI: 10.1039/d1cp04460e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Experimental measurements of the thermal effects of the same osmolytes on two different globular proteins, C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα), have shown that quantifying the change...
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Tavagnacco L, Chiessi E, Zaccarelli E. Molecular insights on poly( N-isopropylacrylamide) coil-to-globule transition induced by pressure. Phys Chem Chem Phys 2021; 23:5984-5991. [PMID: 33666621 PMCID: PMC8247264 DOI: 10.1039/d0cp06452a] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 02/17/2021] [Indexed: 12/17/2022]
Abstract
By using extensive all-atom molecular dynamics simulations of an atactic linear polymer chain, we provide microscopic insights into poly(N-isopropylacrylamide) (PNIPAM) coil-to-globule transition addressing the roles played by both temperature and pressure. We detect a coil-to-globule transition up to large pressures, showing a reentrant behavior of the critical temperature with increasing pressure in agreement with experimental observations. Furthermore, again confirming the experimental findings, we report the existence at high pressures of a new kind of globular state. It is characterized by a more structured hydration shell that is closer to PNIPAM hydrophobic domains, as compared to the globular state observed at atmospheric pressure. Our results highlight that temperature and pressure induce a PNIPAM coil-to-globule transition through different molecular mechanisms, opening the way for a systematic use of both thermodynamic variables to tune the location of the transition and the properties of the associated swollen/collapsed states.
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Affiliation(s)
- Letizia Tavagnacco
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185, Rome, Italy.
| | - Ester Chiessi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, Via della Ricerca Scientifica I, 00133, Rome, Italy.
| | - Emanuela Zaccarelli
- CNR-ISC and Department of Physics, Sapienza University of Rome, Piazzale A. Moro 2, 00185, Rome, Italy.
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Molecular description of the coil-to-globule transition of Poly(N-isopropylacrylamide) in water/ethanol mixture at low alcohol concentration. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2019.111928] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Pica A, Graziano G. Effect of sodium thiocyanate and sodium perchlorate on poly(N-isopropylacrylamide) collapse. Phys Chem Chem Phys 2019; 22:189-195. [PMID: 31799525 DOI: 10.1039/c9cp05706d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The T(collapse) of poly(N-isopropylacrylamide), PNIPAM, shows a nonlinear dependence on the concentration of NaSCN or NaClO4; in the case of NaClO4, for example, at very low concentrations of the salt, T(collapse) increases with the concentration, while it has an opposite trend at higher NaClO4 concentrations [J. Am. Chem. Soc., 2005, 127, 14505]. These puzzling experimental data can be rationalized by considering that low charge density and poorly hydrated ions, such as thiocyanate and perchlorate, interact preferentially with the surface of the polymer, and cause an increase of the magnitude of the energetic term that stabilizes swollen conformations at low salt concentrations. However, as both swollen and collapsed PNIPAM conformations are accessible to such ions in view of their large conformational freedom, the difference in the number of ions bound to PNIPAM surface upon collapse changes little on increasing the salt concentration. Thus, the energetic term that favors swollen conformations increases with salt concentration to a lesser extent than the solvent-excluded volume term (linked to the density increase caused by salt addition to water), that favors collapsed conformations, leading to a nonlinear trend of T(collapse).
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Affiliation(s)
- Andrea Pica
- European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, Grenoble, France
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