Related Experiment Video
Updated: May 18, 2026

08:28
Single-molecule Manipulation of G-quadruplexes by Magnetic Tweezers
Published on: September 19, 2017
Monomer-dimer equilibrium for the 5'-5' stacking of propeller-type parallel-stranded G-quadruplexes: NMR structural
1School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|September 29, 2012
Summary
DNA sequences with guanine-rich motifs can form stable G-quadruplex structures. This study reveals how monomer-dimer equilibrium in these G-quadruplexes is influenced by various factors, providing a structural reference.
Area of Science:
- Biochemistry
- Structural Biology
- Genomics
Background:
- Guanine-rich sequences are prevalent in the human genome.
- These sequences can fold into stable G-quadruplex (G4) structures.
- Propeller-type G4 structures are of interest due to their stability and potential biological roles.
Purpose of the Study:
- To investigate the equilibrium between monomeric and dimeric propeller-type G-quadruplexes.
- To understand the factors influencing this monomer-dimer equilibrium.
- To determine the high-definition solution structure of a representative monomeric G-quadruplex.
Main Methods:
- Nuclear Magnetic Resonance (NMR) spectroscopy was employed.
- Analysis of DNA sequences containing GGGT motifs.
- Investigation of structural parameters and solution conditions.
Main Results:
- The monomer-dimer equilibrium of propeller-type G-quadruplexes is sensitive to DNA concentration, flanking sequences, cation type and concentration, and temperature.
- A high-definition structure of a simple monomeric G-quadruplex with three single-residue loops was determined.
- This structure serves as a valuable reference for propeller-type G-quadruplexes in solution.
Conclusions:
- The formation and stability of G-quadruplexes are highly dependent on specific sequence contexts and environmental conditions.
- Understanding the monomer-dimer equilibrium is crucial for elucidating the biological functions of G-quadruplexes.
- The provided monomeric G-quadruplex structure offers a foundational model for further research in the field.
More Related Videos
Related Concept Videos
¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
Nucleic Acid Structure
The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose's second carbon and a hydrogen on the deoxyribose's second carbon. The phosphate residue attaches to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms a 5′ to 3′ phosphodiester linkage.
DNA Structure
DNA has a double-helix structure. The...
DNA Structure
DNA has a double-helix structure. The...

