Structure of collapsed persistent macromolecule: Toroid vs. spherical globule

Vasilevskaya, V. V.; Khokhlov, A. R.; Kidoaki, Satoru; Yoshikawa, Kazunori

doi:10.1002/(sici)1097-0282(199701)41:1<51::aid-bip5>3.3.co;2-u

Cited by 39 publications

(66 citation statements)

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“…The globule shape of long amphiphilic polymers depends both on chain stiffness and on kinetic factors, so that stiff macromolecules can form coexisting collagen-like, toroidal, and disklike globules. Note that the degree of polymerization dependence of the shape of the phase diagram for a stiff-chain macromolecule was discussed in a series of papers [3][4] for homopolymeric macromolecules. It was shown therein that collapsing stiff-chain macromolecules pass the three stages: coil -toroidal globule -spherical globule, and the higher the degree of polymerization is, the narrower is the range of parameters allowing the existence of a toroidal globule.…”

Section: Results and Analysismentioning

confidence: 99%

“…Note, that also almost no systematic experiments have been performed to study structural conversions of stiff-chain macromolecules during coil-globule transitions. As far as we know, only one paper has been published so far [3] on the study of the solvent quality dependence of globule's shape of DNA double helix. Therein was, in fact, the prediction made (and verified) that the toroidal globule is an intermediate stage between the coil and the spherical globule.…”

Section: Results and Analysismentioning

confidence: 99%

“…No wonder, therefore, that stiff chain macromolecules have been extensively studied over the last several decades. [1][2][3][4][5][6][7] The ability to form globules of a complex form is one of the most remarkable properties of stiff-chain macromolecules. Thus, the DNA double helix is known to fold to a toroidal structure in vivo, within bacteriophage capsule, and in vitro during compactization in solutions of multivalent ions and surfactants.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10][11][12][13][14][15][16] Toroidal globules are formed by stiff-chain macromolecules of relatively small length and are intermediate states between coil and spherical globule in the conformational state vs. solvent quality phase diagram. [3][4]6] A rodlike globule is another unusual conformation of stiff-chain macromolecules: the chain just folds onto itself several times. Rod-like globules co-exist with toroidal globules.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11][12][13][14][15][16] Homopolymer molecules with persistence or freely jointed flexibility mechanism are usually considered in theoretical and computer simulation studies. [1][2][3][4][5][6][7] However, many macromolecules (including a single-chain DNA and proteins) are amphiphilic, i.e. each monomer unit contains both hydrophobic and hydrophilic groups.…”

Section: Introductionmentioning

confidence: 99%

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Diagram of State of Stiff Amphiphilic Macromolecules

Марков

Vasilevskaya

Khalatur

et al. 2007

Macromolecular Symposia

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Summary: We studied coil‐globule transitions in stiff‐chain amphiphilic macromolecules via computer modeling and constructed phase diagrams for such molecules in terms of solvent quality and persistence length. We showed that the shape of the phase diagram essentially depends on the macromolecule degree of polymerization. Relatively short amphiphilic molecules always form a spherical globule in a poor solvent, and the coil‐globule transition includes one or two intermediate conformations, depending on the chain's stiffness. These are a disk‐like globule in case of high enough Kuhn segment length, and a pearl necklace‐like structure of spherical micelles and a disk‐like globule in case of relatively flexible chains. The phase diagram of a long stiff amphiphilic chain was found to be more complex still. Thus three specific regions can be distinguished in the poor solvent region, depending on the chain stiffness. These correspond to a cylindrical globule without any specific backbone ordering, a cylindrical globule containing blobs with collagen‐like ordering of the chain, and co‐existence of collagen‐like and toroidal globules. In the intermediate transition region in this case, apart from the pearl necklace‐like conformations with spherical micelles, necklace conformations can be also observed where the polymeric chain has collagen‐like ordering within each bead.

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Section: Results and Analysismentioning

confidence: 99%

Section: Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Diagram of State of Stiff Amphiphilic Macromolecules

Марков

Vasilevskaya

Khalatur

et al. 2007

Macromolecular Symposia

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DNA condensation by multivalent cations

1997

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In the presence of multivalent cations, high molecular weight DNA undergoes a dramatic condensation to a compact, usually highly ordered toroidal structure. This review begins with an overview of DNA condensation:condensing agents, morphology, kinetics and reversibility, and the minimum size required to form orderly condensates. It then summarizes the statistical mechanics of the collapse of stiff polymers, which shows why DNA condensation is abrupt and why toroids are favored structures. Various ways to estimate or measure intermolecular forces in DNA condensation are discussed, all of them agreeing that the free energy change per base pair is very small, on the order of 1% of thermal energy. Experimental evidence is surveyed showing that DNA condensation occurs when about 90% of its charge is neutralized by counterions. The various intermolecular forces whose interplay gives rise to DNA condensation are then reviewed. The entropy loss upon collapse of the expanded wormlike coil costs free energy, and stiffness sets limits on tight curvature. However, the dominant contributions seem to come from ions and water. Electrostatic repulsions must be overcome by high salt concentrations or by the correlated fluctuations of territorially bound multivalent cations. Hydration must be adjusted to allow a cooperative accommodation of the water structure surrounding surface groups on the DNA helices as they approach. Undulations of the DNA in its confined surroundings extend the range of the electrostatic forces. The condensing ions may also subtly modify the local structure of the double helix.

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Chain length dependence of folding transition in a semiflexible homo-polymer chain: Appearance of a core–shell structure

Higuchi

Sakaue

Yoshikawa

2008

Chemical Physics Letters

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The folding transition of single, long semiflexible polymers was studied with special emphasis on the chain length effect using Monte Carlo simulations. While a relatively short chain (10-25 Kuhn segments) undergoes a large discrete transition between swollen coil and compact toroid conformations, a long chain (50 Kuhn segments) exhibits an intrachain segregated state between the disordered coil and ordered toroid.

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Structure of collapsed persistent macromolecule: Toroid vs. spherical globule

Cited by 39 publications

References 0 publications

Diagram of State of Stiff Amphiphilic Macromolecules

Diagram of State of Stiff Amphiphilic Macromolecules

DNA condensation by multivalent cations

Chain length dependence of folding transition in a semiflexible homo-polymer chain: Appearance of a core–shell structure

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