Abstract
In considering supercoils formed by closed double-stranded molecules of DNA certain mathematical concepts, such as the linking number and the twist, are needed. The meaning of these for a closed ribbon is explained and also that of the writhing number of a closed curve. Some simple examples are given, some of which may be relevant to the structure of chromatin.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Depew D. E., Wang J. C. Conformational fluctuations of DNA helix. Proc Natl Acad Sci U S A. 1975 Nov;72(11):4275–4279. doi: 10.1073/pnas.72.11.4275. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fuller F. B. The writhing number of a space curve. Proc Natl Acad Sci U S A. 1971 Apr;68(4):815–819. doi: 10.1073/pnas.68.4.815. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Germond J. E., Hirt B., Oudet P., Gross-Bellark M., Chambon P. Folding of the DNA double helix in chromatin-like structures from simian virus 40. Proc Natl Acad Sci U S A. 1975 May;72(5):1843–1847. doi: 10.1073/pnas.72.5.1843. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Griffith J. D. Chromatin structure: deduced from a minichromosome. Science. 1975 Mar 28;187(4182):1202–1203. doi: 10.1126/science.187.4182.1202. [DOI] [PubMed] [Google Scholar]
- Keller W. Determination of the number of superhelical turns in simian virus 40 DNA by gel electrophoresis. Proc Natl Acad Sci U S A. 1975 Dec;72(12):4876–4880. doi: 10.1073/pnas.72.12.4876. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keller W., Wendel I. Stepwise relaxation of supercoiled SV40 DNA. Cold Spring Harb Symp Quant Biol. 1975;39(Pt 1):199–208. doi: 10.1101/sqb.1974.039.01.026. [DOI] [PubMed] [Google Scholar]
- Liu L. F., Wang J. C. On the degree of unwinding of the DNA helix by ethidium. II. Studies by electron microscopy. Biochim Biophys Acta. 1975 Jul 23;395(4):401–412. [PubMed] [Google Scholar]
- Pulleyblank D. E., Morgan A. R. The sense of naturally occurring superhelices and the unwinding angle of intercalated ethidium. J Mol Biol. 1975 Jan 5;91(1):1–13. doi: 10.1016/0022-2836(75)90368-x. [DOI] [PubMed] [Google Scholar]
- Pulleyblank D. E., Shure M., Tang D., Vinograd J., Vosberg H. P. Action of nicking-closing enzyme on supercoiled and nonsupercoiled closed circular DNA: formation of a Boltzmann distribution of topological isomers. Proc Natl Acad Sci U S A. 1975 Nov;72(11):4280–4284. doi: 10.1073/pnas.72.11.4280. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang J. C. The degree of unwinding of the DNA helix by ethidium. I. Titration of twisted PM2 DNA molecules in alkaline cesium chloride density gradients. J Mol Biol. 1974 Nov 15;89(4):783–801. doi: 10.1016/0022-2836(74)90053-9. [DOI] [PubMed] [Google Scholar]