Structure of collapsed persistent macromolecule: Toroid vs. spherical globule

V. V. Vasilevskaya, A. R. Khokhlov, S. Kidoaki, K. Yoshikawa

Research output: Contribution to journalArticlepeer-review

107 Citations (Scopus)


We studied theoretically the behavior of a collapsed persistent macromolecule in poor solvent as a model of collapse transition of single double-stranded DNA chain, and constructed the diagram of states in the variables with contour length of a macromolecule and quality of the solvent. We found that the state of toroidal globule exists as an intermediate state between the states of elongated coil state and the spherical globule. Our theoretical result suggests that a single linear macromolecule with a high degree of polymerization can form a toroidal globule. However, the range in which the toroidal structure is stable decreases as the macromolecule length increases. Experimental observation with transmission electron microscopy has been performed to study the globular structure of single DNA chain (bacteriophage T4 DNA, λ-DNA) collapsed by hexammine cobalt (III) at different concentrations. We found that an extremely long chain of T4 DNA (166 kbp), with a contour length of 56 μm. actually forms a toroidal globule, and that isotropic spherical globule appears at higher hexammine cobalt concentration.

Original languageEnglish
Pages (from-to)51-60
Number of pages10
Issue number1
Publication statusPublished - 1997
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Biomaterials
  • Organic Chemistry


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