Related Experiment Video
Updated: Aug 5, 2026
11:25
A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1
Published on: March 18, 2017
A lead-filled G-quadruplex: insight into the G-Quartet's selectivity for Pb(2+) over K(+)
1Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
Organic Letters
|October 13, 2000
Summary
A lipophilic nucleoside, G 1, effectively extracts lead(II) picrate (Pb(2+)) into organic solvents, forming G-quartet structures. Lead(II) forms a more compact G(8) cage than potassium(I) (K(+)), enhancing hydrogen bond stability.
Area of Science:
- Supramolecular Chemistry
- Coordination Chemistry
- Biophysical Chemistry
Background:
- G-quartets are nucleic acid structures stabilized by Hoogsteen hydrogen bonds.
- Metal ions play crucial roles in stabilizing G-quartet structures.
- Understanding metal-G-quartet interactions is vital for applications in molecular recognition and sensing.
Purpose of the Study:
- To investigate the extraction of lead(II) picrate using a lipophilic nucleoside G 1.
- To elucidate the structural differences between lead(II)- and potassium(I)-templated G-quartets.
- To correlate structural findings with nuclear magnetic resonance (NMR) data on hydrogen bond stability.
Main Methods:
- Liquid-liquid extraction of lead(II) picrate using G 1.
- X-ray crystallography to determine the structures of metal-G-quartet complexes.
- Nuclear Magnetic Resonance (NMR) spectroscopy to assess hydrogen bond dynamics.
Main Results:
- G 1 successfully extracts Pb(2+) picrate into organic solvents, forming octameric G-quartet structures.
- Crystal structures reveal that Pb(2+) templates a smaller G(8) cage compared to K(+).
- NMR data show increased kinetic stability of N2-N7 hydrogen bonds in the Pb(2+)-G-quartet complex.
Conclusions:
- The lipophilic nucleoside G 1 is effective for selective extraction of Pb(2+).
- Pb(2+) induces a more compact G-quartet structure than K(+), influencing complex stability.
- The study provides insights into metal ion selectivity and structural templating in G-quartet systems.
Related Concept Videos
03:07Solubility Equilibria
Solubility equilibria are established when the dissolution and precipitation of a solute species occur at equal rates. These equilibria underlie many natural and technological processes, ranging from tooth decay to water purification. An understanding of the factors affecting compound solubility is, therefore, essential to the effective management of these processes. This section applies previously introduced equilibrium concepts and tools to systems involving dissolution and precipitation.
The...
The...
04:01Factors Affecting Solubility
Compared with pure water, the solubility of an ionic compound is less in aqueous solutions containing a common ion (one also produced by dissolution of the ionic compound). This is an example of a phenomenon known as the common ion effect, which is a consequence of the law of mass action that may be explained using Le Chȃtelier’s principle. Consider the dissolution of silver iodide:
03:11Precipitation of Ions
Predicting Precipitation
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
The equation that describes the equilibrium between solid calcium carbonate and its solvated ions is:
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
01:19Mass Analyzers: Common Types
The quadrupole mass analyzer consists of four cylindrical metal rods arranged in a diamond carrying a DC voltage and a radio-frequency AC voltage. The motion of ions through the quadrupole depends on the field strength, causing only ions of a certain m/z to resonate successfully and strike the detector at a given field strength. Though the transmission rate for these analyzers is high, the exact elemental composition of the sample is not determined because of low resolution; however, they are...
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...