Two states do not necessarily correspond to a two-state transition: van’t Hoff enthalpy in the case of a small entropy difference between the states

Bakk, Audun; Metzler, Ralf

doi:10.1016/j.cplett.2004.09.052

Cited by 7 publications

(9 citation statements)

References 13 publications

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“…Thus, a maximum in C v is commonly interpreted as the “breaking” of multiple non-covalent molecular contacts that are important for the co-existence of more than one stable configuration in the system. Additionally, qualitative features of this maximum in C v (e.g., the height and breadth of the peak, as well as the temperature at which this peak occurs) also provide information regarding the stability of the species involved in the transition as they are related to the change in internal energy during the transition (Δ U ) 53,54 Typically, short and/or broad C v profiles are associated with poorly cooperative, unstructured species as they correspond to small Δ U , and vice-versa. Therefore, the results in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, qualitative features of this maximum in C v (e.g., the height and breadth of the peak, as well as the temperature at which this peak occurs) also provide information regarding the stability of the species involved in the transition as they are related to the change in internal energy during the transition (DU). 53,54 Typically, short and/or broad C v Fig. 2 DLS was used to measure the average R h value of PAA-VG2.…”

Section: Simulations Of Conjugates and Parent Materialsmentioning

confidence: 99%

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Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

et al. 2015

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Polymer-peptide conjugates were produced via the copper-catalyzed alkyne-azide cycloaddition of poly(tert butyl acrylate) (PtBA) and elastin-like peptides. An azide-functionalized polymer was produced via atom-transfer radical polymerization (ATRP) followed by conversion of bromine end groups to azide groups. Subsequent reaction of the polymer with a bis-alkyne-functionalized, elastin-like peptide proceeded with high efficiency, yielding di- and tri-block conjugates, which after deprotection, yielded poly(acrylic acid) (PAA)-based diblock and triblock copolymers. These conjugates were solubilized in dimethyl formamide, and titration of phosphate buffered saline (PBS) induced aggregation. The presence of polydisperse spherical aggregates was confirmed by dynamic light scattering and transmission electron microscopy. Additionally, a coarse-grained molecular model was designed to reasonably capture inter- and intramolecular interactions for the conjugates and its precursors. This model was used to assess the effect of the different interacting molecular forces on the conformational thermodynamic stability of the copolymers. Our results indicated that the PAA’s ability to hydrogen-bond with both itself and the peptide is the main interaction for stabilizing the diblocks and triblocks and driving their self-assembly, while interactions between peptides are suggested to play only a minor role on the conformational and thermodynamic stability of the conjugates.

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Section: Resultsmentioning

confidence: 99%

Section: Simulations Of Conjugates and Parent Materialsmentioning

confidence: 99%

Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

et al. 2015

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“…The values of the enthalpy of transfer can be derived from data referring to the temperature dependence of the partition coefficients, generally interpreted by means of the linear van't Hoff equations. 31 ) (δ∆trH o /δT), is not zero. This leads to curvatures in the van't Hoff plots.…”

Section: Salt Effects In the [M(cn) 5 No]mentioning

confidence: 93%

“…The values of the enthalpy of transfer can be derived from data referring to the temperature dependence of the partition coefficients, generally interpreted by means of the linear van't Hoff equations. 31 Figures 7, 8, and 9 show van't Hoff plots of ln K versus 1/T for complexes of iron, manganese, and chromium, respectively, in ATPS formed with Na 2 SO 4 /PEO/ H 2 O.…”

Section: Stability Of the Anionmentioning

confidence: 99%

PEO−[M(CN)₅NO]^x- (M = Fe, Mn, or Cr) Interaction as a Driving Force in the Partitioning of the Pentacyanonitrosylmetallate Anion in ATPS: Strong Effect of the Central Atom

Silva

Francisco

et al. 2008

J. Phys. Chem. B

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The partitioning behavior of pentacyanonitrosilmetallate complexes[Fe(CN) 5 NO] (2-), [Mn(CN) 5 NO] 3(-), and [Cr(CN) 5 NO] 3(-)has been studied in aqueous two-phase systems (ATPS) formed by adding poly(ethylene oxide) (PEO; 4000 g mol (-1)) to an aqueous salt solution (Li2 SO4, Na2 SO4, CuSO4, or ZnSO4). The complexes partition coefficients ( K complex) in each of these ATPS have been determined as a function of increasing tie-line length (TLL) and temperature. Unlike the partition behavior of most ions, [Fe(CN) 5 NO] 2(-) and [Mn(CN) 5 NO] 3(-) anions are concentrated in the polymer-rich phase with K values depending on the nature of the central atom as follows: K [Fe(C N) 5 NO] 2 - >> K [ Mn (CN 5 NO] 3 - > K [C r (C N) 5 NO ]3 - . The effect of ATPS salts in the complex partitioning behavior has also been verified following the order Li2 SO 4 > Na2 SO 4 > ZnSO4. Thermodynamic analysis revealed that the presence of anions in the polymer-rich phase is caused by an EO-[M(CN) 5 NO] ( x- ) (M = Fe, Mn, or Cr) enthalpic interaction. However, when this enthalpic interaction is weak, as in the case of the [Cr(CN) 5 NO]3(-) anion ( K [Cr(CN 5 NO] 3 - < 1), entropic driving forces dominate the transfer process, then causing the anions to concentrate in the salt-rich phase.

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“…However, it has been shown that three-state, or even N-state folders can theoretically have a van't Hoff ratio of 1, the value for ideal 2-state folding. 33,[35][36][37] To analyze the thermodynamic behavior of complex knotting systems with 3 or more configurational states, we deconstruct the total heat capacity curve into contributions from each individual configurational state, and contributions from each state-to-state transition. The sum of the individual state terms weighted by their population fraction represent a 'baseline' heat capacity, while each transition term can be viewed as a cooperativity metric of that transition.…”

Section: Introductionmentioning

confidence: 99%

How cooperatively folding are homopolymer molecular knots?

Walker¹,

Fobe²,

Shirts³

2022

Preprint

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Detailed thermodynamic analysis of complex systems with multiple stable configurational states allows for insight into the cooperativity of each individual transition. In this work we derive a heat capacity decomposition comprising contributions from each individual configurational state, which together sum to a baseline heat capacity, and contributions from each state-to-state transition. We apply this analysis framework to a series of replica exchange molecular dynamics simulations of linear and 1-1 coarsegrained homo-oligomer models which fold into stable, configurationally well-defined molecular knots, in order to better understand the parameters leading to stable and cooperative folding of these knots. We find that a stiff harmonic backbone bending angle potential is key to achieving knots with specific 3D structures. Tuning the backbone equilibrium angle in small increments yields a variety of knot topologies, including 3 1 , 5 1 , 7 1 , and 8 19 types. Populations of different knotted states as functions of temperature can also be manipulated by tuning backbone torsion stiffness or by adding side chain beads. We find that sharp total heat capacity peaks for the homo-oligomer knots are largely due to a coil-to-globule transition, rather than a cooperative knotting step. However, in some cases the cooperativity of globule-to-knot and coil-to-globule transitions are comparable, suggesting that highly cooperative folding to knotted structures can be achieved by refining the model parameters or adding sequence specificity.

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Two states do not necessarily correspond to a two-state transition: van’t Hoff enthalpy in the case of a small entropy difference between the states

Cited by 7 publications

References 13 publications

Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

PEO−[M(CN)₅NO]^x- (M = Fe, Mn, or Cr) Interaction as a Driving Force in the Partitioning of the Pentacyanonitrosylmetallate Anion in ATPS: Strong Effect of the Central Atom

How cooperatively folding are homopolymer molecular knots?

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Two states do not necessarily correspond to a two-state transition: van’t Hoff enthalpy in the case of a small entropy difference between the states

Cited by 7 publications

References 13 publications

Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

Aggregation of poly(acrylic acid)-containing elastin-mimetic copolymers

PEO−[M(CN)5NO]x- (M = Fe, Mn, or Cr) Interaction as a Driving Force in the Partitioning of the Pentacyanonitrosylmetallate Anion in ATPS: Strong Effect of the Central Atom

How cooperatively folding are homopolymer molecular knots?

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Product

Resources

About

PEO−[M(CN)₅NO]^x- (M = Fe, Mn, or Cr) Interaction as a Driving Force in the Partitioning of the Pentacyanonitrosylmetallate Anion in ATPS: Strong Effect of the Central Atom