[资料，科普] A-form, B-form, Z-form DNA 及其 X射线衍射照片

一、A型、B型、Z型 DNA： A-form, B-form, Z-form DNA

图1  Different-forms-of-DNA-768x403.webp

https://microbenotes.com/wp-content/uploads/2019/04/Different-forms-of-DNA-768x403.jpg  

https://microbenotes.com/different-forms-of-dna-b-form-a-form-z-form/

图2  800px-Dnaconformations.png

B-form (left), A-form (middle) and Z-DNA (right). (CC BY-SA 4.0; Mauroesguerroto)

https://bio.libretexts.org/Bookshelves/Genetics/Working_with_Molecular_Genetics_(Hardison)/Unit_I%3A_Genes_Nucleic_Acids_Genomes_and_Chromosomes/2%3A_Structures_of_Nucleic_Acids/2.5%3A_B-Form_A-Form_and_Z-Form_of_DNA

图3  molecules-28-00843-g004.webp

https://pub.mdpi-res.com/molecules/molecules-28-00843/article_deploy/html/images/molecules-28-00843-g004.png?1674053733

https://www.mdpi.com/1420-3049/28/2/843

图4  3dna-nar03-fig9.jpeg

http://docs.x3dna.org/images/3dna-nar03-fig9.jpeg

图5  symmetry-12-00737-g004.png

https://www.mdpi.com/symmetry/symmetry-12-00737/article_deploy/html/images/symmetry-12-00737-g004.png

   Canonical double-helical forms of DNA based on X-ray fiber diffraction analysis. Twelve-base-pair fragments of calf thymus A-DNA and B-DNA with arbitrary sequence dATCGATCGATCG and of Z-DNA with alternating sequence dCGCGCGCGCGCG. In the top row, the straight helix axis is vertical, and the view is into the minor groove at the helix center. The bottom row presents the view down the helix axis after 90° rotation. The antiparallel strands are drawn with different colors, and the sugar-phosphate backbone is depicted as smooth tube. Models were generated with Web 3DNA 2.0 [48] based on coordinates derived from X-ray fiber diffraction [46,47] and drawn with PyMOL [28].

   基于X射线纤维衍射分析的DNA典型双螺旋形式。小牛胸腺A-DNA和B-DNA的12个碱基对片段，具有任意序列dATCGATCGATCG和Z-DNA的交替序列dCGCGCGCGCG。在顶行中，直螺旋轴是垂直的，视图位于螺旋中心的小凹槽中。最下面一行显示了旋转90°后沿螺旋轴的视图。反平行的链被绘制成不同的颜色，糖磷酸盐骨架被描绘成光滑的管状。

https://www.mdpi.com/2073-8994/12/5/737

二、X射线衍射成像

图6  x-ray-crytallography-figure-3.png

https://wiki.anton-paar.com/fileadmin/wiki/images/22046_X-ray-crystallography/x-ray-crytallography-figure-3.png

Schematic depiction of the generation of an X-ray diffraction pattern of a single crystal.

https://wiki.anton-paar.com/ae-en/x-ray-crystallography/

三、X射线衍射图片

图7  4-Figure1-1.png

   Figure 1. The five major conformational variants of the DNA double helix, their helix parameters and their X-ray fibrediffraction patterns. The A, B, C, D and Z structures are described in Fuller et al. (1965), Langridge et al. (1960 a and b), Marvin et al. (1961), Arnott et al. (1983) and Arnott et al. (1980), respectively.

https://www.semanticscholar.org/paper/Water-DNA-interactions-as-studied-by-X-ray-and-Fuller-Forsyth/54faa6135db14570f9ed503c51c760aff2b70044

图8  7-Figure5-1.png

   Figure 5. X-ray fibre-diffraction patterns recorded during a water-driven transition between the D and the B conformations of DNA. The data were recorded at the Daresbury SRS using an online image plate system (see text for description of the features in the diffraction patterns). 

https://www.semanticscholar.org/paper/Water-DNA-interactions-as-studied-by-X-ray-and-Fuller-Forsyth/54faa6135db14570f9ed503c51c760aff2b70044

图9  7-Figure6-1.png

   Figure 6. Series of diffraction patterns recorded during the water-driven transition between the A and Z conformations of poly[d(G–m5C)].poly[d(G–m5C)] (see § 3 for discussion of the features in the diffraction patterns). RH, relative humidity.

https://www.semanticscholar.org/paper/Water-DNA-interactions-as-studied-by-X-ray-and-Fuller-Forsyth/54faa6135db14570f9ed503c51c760aff2b70044

参考资料：

[1] 2025-11-11，DNA双螺旋/DNA double helix/关一夫，中国大百科全书，第三版网络版[DB/OL]

https://www.zgbk.com/ecph/words?SiteID=1&ID=127776&Type=bkzyb&SubID=109743

   由两条互补的多聚脱氧核苷酸链反向平行所形成的螺旋构象。通常指B型双螺旋或B型DNA。

   除了B型DNA，还有A型DNA和Z型DNA。

   在不同的环境(例如盐浓度、湿度)条件下和/或不同的脱氧核苷酸序列，双链DNA分子可呈现不同类型的双螺旋。当实验条件由较大的相对湿度转变为<75%时，B型DNA可转变为A型DNA。A型DNA与B型DNA一样，核苷酸为反式(见脱氧核苷酸)，也是右手双螺旋；两者不同的是，A型DNA螺旋直径比B型DNA大，同一链上相邻碱基对之间的转角为33°，每周含有11个核苷酸残基。Z型DNA的多聚脱氧核苷酸链为反式嘧啶核苷酸残基与顺式嘌呤核苷酸残基交替出现的序列，多见反式胞嘧啶或反式5-甲基胞嘧啶与顺式鸟嘌呤交替出现的序列；呈左手“Z”形双螺旋构象，直径较短，每周含有12个核苷酸残基。存在于活细胞内的DNA是B型DNA，在部分序列中有Z型DNA存在。

[2] Watson Fuller, Trevor Forsyth, Arumugam Mahendrasingam. Water-DNA interactions as studied by X-ray and neutron fibre diffraction [J]. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2004, 359(1448): 1237-1248

doi:  10.1098/rstb.2004.1501

https://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC1693411&blobtype=pdf

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https://blog.sciencenet.cn/blog-107667-1512190.html

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