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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/12/06 12:39:34」(JST)
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Ropes have superhelical structures
A superhelix is a molecular structure in which a helix is itself coiled into a helix. This is significant to both proteins and genetic material, such as overwound circular DNA.
The earliest significant reference in molecular biology is from 1971, by F.B. Fuller:
- A geometric invariant of a space curve, the writhing number, is defined and studied. For the central curve of a twisted cord the writhing number measures the extent to which coiling of the central curve has relieved local twisting of the cord. This study originated in response to questions that arise in the study of supercoiled double-stranded DNA rings.[1]
About the writhing number, mathematician W.F. Pohl says:
- It is well known that the writhing number is a standard measure of the global geometry of a closed space curve.[2]
Contrary to intuition, a topological property, the linking number, arises from the geometric properties twist and writhe according to the following relationship:
- Lk = T + W,
where Lk is the linking number, W is the writhe and T is the twist of the coil.
The linking number refers to the number of times that one strand wraps around the other. In DNA this property does not change and can only be modified by specialized enzymes called topoisomerases.
See also
References
- ^ Fuller, F. Brock (1971). "The writhing number of a space curve". Proceedings of the National Academy of Sciences. 68 (4): 815–819. doi:10.1073/pnas.68.4.815. MR 0278197. PMC 389050. PMID 5279522.
- ^ Pohl, William F. (1968). "The self-linking number of a closed space curve". Journal of Mathematics and Mechanics. 17 (10): 975–985. doi:10.1512/iumj.1968.17.17060. MR 0222777.
External links
- Calugareanu Theorem - From Wolfram Research's MathWorld.
- Writhe - From MathWorld.
- Twist - From MathWorld.
- DNA Structure and Topology at Molecular Biochemistry II: The Bello Lectures.
English Journal
- Structures of archaeal DNA segregation machinery reveal bacterial and eukaryotic linkages.
- Schumacher MA1, Tonthat NK2, Lee J2, Rodriguez-Castañeda FA3, Chinnam NB2, Kalliomaa-Sanford AK3, Ng IW3, Barge MT3, Shaw PL2, Barillà D4.
- Science (New York, N.Y.).Science.2015 Sep 4;349(6252):1120-4. doi: 10.1126/science.aaa9046.
- Although recent studies have provided a wealth of information about archaeal biology, nothing is known about the molecular basis of DNA segregation in these organisms. Here, we unveil the machinery and assembly mechanism of the archaeal Sulfolobus pNOB8 partition system. This system uses three prote
- PMID 26339031
- Modelling of the N-terminal section and the lumenal loop of trimeric light harvesting complex II (LHCII) by using EPR.
- Fehr N1, Dietz C2, Polyhach Y3, von Hagens T3, Jeschke G3, Paulsen H4.
- The Journal of biological chemistry.J Biol Chem.2015 Aug 27. pii: jbc.M115.669804. [Epub ahead of print]
- The major light harvesting complex II (LHCII) of green plants plays a key role in the absorption of sunlight, the regulation of photo-synthesis, and in preventing photo-damage by excess light. The latter two functions are thought to involve the lumenal loop and the N-terminal domain. Their structure
- PMID 26316535
- Structural Studies Reveal the Functional Modularity of the Scc2-Scc4 Cohesin Loader.
- Chao WC1, Murayama Y1, Muñoz S1, Costa A2, Uhlmann F1, Singleton MR3.
- Cell reports.Cell Rep.2015 Aug 4;12(5):719-25. doi: 10.1016/j.celrep.2015.06.071. Epub 2015 Jul 23.
- The remarkable accuracy of eukaryotic cell division is partly maintained by the cohesin complex acting as a molecular glue to prevent premature sister chromatid separation. The loading of cohesin onto chromosomes is catalyzed by the Scc2-Scc4 loader complex. Here, we report the crystal structure of
- PMID 26212329
Japanese Journal
- Polar superhelices in ferroelectric chiral nanosprings
- OS1404-210 強誘電ナノスプリングにおける超らせん分極と高次秩序変数の力学的創出
- 細胞極性タンパク質LGNとパートナー分子mInsc複合体の認識機構
Related Links
- superhelixとは。意味や和訳。[名詞] 〔生化学〕 スーパーヘリックス，超らせん：環状の二重らせん DNA 全体が，さらにらせん状にねじれたもの. (また supercoil)[語源]1964superhelical [形容詞]superhelicity [名詞] - 80万項目以上収録 ...
- Define superhelix. superhelix synonyms, superhelix pronunciation, superhelix translation, English dictionary definition of superhelix. n. pl. su·per·he·lix·es or su·per·hel·i·ces A molecular structure in which a helix is itself coiled into ...
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