Related Experiment Video
Updated: May 11, 2026
05:37
Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
Published on: April 4, 2025
A photoresponsive supramolecular G-quadruplex
José M Rivera1, Diana Silva-Brenes
1Department of Chemistry, University of Puerto Rico , Río Piedras Campus, Río Piedras, Puerto Rico 00931.
Organic Letters
|May 7, 2013
Summary
Photoirradiation of G-quadruplex DNA induces a [2 + 2] cyclodimerization reaction. This transformation favors the formation of a specific heteromeric octamer structure from the hexadecameric assembly.
Area of Science:
- Supramolecular chemistry
- Photochemistry
- Nucleic acid structures
Background:
- G-quadruplexes are four-stranded nucleic acid structures with diverse biological roles.
- Supramolecular assemblies offer platforms for precise molecular organization and reactivity.
Purpose of the Study:
- To investigate the photochemical reactivity of hexadecameric supramolecular G-quadruplexes.
- To explore the potential for photoinduced transformations to control G-quadruplex assembly.
Main Methods:
- Photoirradiation of hexadecameric G-quadruplexes.
- Analysis of reaction products using spectroscopic and structural techniques.
Main Results:
- A diastereoselective [2 + 2] cyclodimerization occurred in half of the constituent subunits upon photoirradiation.
- The cyclodimerization event shifted the equilibrium, leading to the formation of a defined heteromeric octamer.
Conclusions:
- Photochemical reactions can be harnessed to precisely modify and assemble G-quadruplex structures.
- This study demonstrates a novel pathway for creating specific G-quadruplex architectures.
Related Concept Videos
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:29The Photochemical Reaction Center
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...