Related Experiment Video
Updated: Jan 31, 2026
12:38
Structure of HIV-1 Capsid Assemblies by Cryo-electron Microscopy and Iterative Helical Real-space Reconstruction
Published on: August 9, 2011
17.8K
Crystal structures of disordered Z-type helices.
S Karthik1, P K Mandal1, A Thirugnanasambandam1
1a Centre of Advanced Study in Crystallography and Biophysics , University of Madras, Guindy Campus , Chennai , Tamil Nadu , India.
Nucleosides, Nucleotides & Nucleic Acids
|December 28, 2018
Summary
X-ray crystallography reveals left-handed Z-type helices in two alternating pyrimidine-purine DNA sequences. These structures exhibit unique
Area of Science:
- Structural biology
- Biochemistry
- Crystallography
Background:
- DNA can adopt various helical structures beyond the canonical B-form.
- Left-handed Z-DNA helices are known for their alternating purine-pyrimidine sequences.
Purpose of the Study:
- To determine the X-ray crystal structures of two specific alternating pyrimidine-purine DNA sequences.
- To analyze the helical structures and packing arrangements of these DNA sequences.
Main Methods:
- X-ray crystallography was used to obtain high-resolution structural data.
- Analysis of the crystal structures to elucidate DNA conformation and intermolecular interactions.
Main Results:
- The decamer d(CGCGTACGCG)2 and tetradecamer d(CGCGCGTACGCGCG)2 sequences were crystallized.
- Both sequences adopted disordered, pseudo-continuous left-handed Z-type helical conformations.
- The observed packing mode featured 'bundles of columns of helices' with novel variations.
Conclusions:
- Alternating pyrimidine-purine sequences can form stable left-handed Z-DNA helices.
- The crystal structures provide insights into DNA polymorphism and molecular recognition.
- The unique packing arrangements highlight the diverse ways DNA molecules can organize in the solid state.
More Related Videos
Related Concept Videos
02:42Ionic Crystal Structures
17.0K
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
17.0K
01:30Pleural Disorders: Types and Brief Description
690
The pleura is a vital part of the respiratory system. It's a double-layered membrane surrounding the lungs and lining the chest cavity. The two layers of the pleura are:
690
01:28Types of Non-structural Cracks in Concrete
505
Non-structural cracks are primarily of three types: plastic, early-age thermal, and drying shrinkage cracks. Plastic cracks are further classified into plastic shrinkage cracks and plastic settlement cracks.
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
Plastic shrinkage cracks typically form within hours after the concrete is poured. The concrete's surface dries faster than the bottom, creating tensile stress that the still-plastic concrete cannot withstand, leading to diagonal or randomly patterned cracks on the concrete surface.
505
02:18Intrinsically Disordered Proteins
19.4K
Intrinsically disordered proteins are a group of proteins that do not fold into specific three-dimensional structures. Their structural flexibility allows them to complement ordered proteins to perform functions that are inaccessible to rigid structures. They are more common in eukaryotes than prokaryotes and may either be exclusively intrinsically disordered or hybrid proteins, consisting of a mix of ordered and disordered regions. The absence of a rigid structure in these proteins can be...
19.4K
02:58Crystal Field Theory - Octahedral Complexes
30.8K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
30.8K
01:20Accessory Structures of the Skin: Hair Growth and Types
2.4K
Hair growth begins with the production of keratinocytes by the basal cells of the hair bulb. As new cells are deposited at the hair bulb, the hair shaft is pushed through the follicle toward the surface. Keratinization is completed as the cells are pushed to the skin surface to form the shaft of hair that is externally visible. The external hair is completely dead and composed entirely of keratin. Hair can be cut or shaven without damaging the hair structure because the cut is superficial. Most...
2.4K