Related Experiment Video
Updated: Jun 4, 2026
12:05
A Simple, Robust, and High Throughput Single Molecule Flow Stretching Assay Implementation for Studying Transport of Molecules Along DNA
Published on: October 1, 2017
Single-step charge transport through DNA over long distances
Joseph C Genereux1, Stephanie M Wuerth, Jacqueline K Barton
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|February 26, 2011
Summary
Charge transport in DNA occurs coherently in a single step across 7 or 8 adenine bases. This finding reveals a transition from multistep to single-step charge transport with increasing separation, favoring DNA
Area of Science:
- Molecular Biology
- Biophysics
- Organic Chemistry
Background:
- Charge transport through DNA is crucial for biological processes.
- Understanding DNA charge transport mechanisms is key to developing novel molecular electronics and DNA-based sensors.
Purpose of the Study:
- To measure quantum yields for charge transport across adenine tracts of varying lengths.
- To differentiate between single-step and multistep charge transport mechanisms in synthetic oligonucleotides.
- To investigate the influence of donor/acceptor separation on DNA charge transport pathways.
Main Methods:
- Utilized fluorescence quenching to measure hole injection efficiency.
- Employed hole trapping by a cyclopropyl guanine derivative to monitor charge transport.
- Synthesized oligonucleotides with photoexcited 2-aminopurine and N(2)-cyclopropyl guanine.
Main Results:
- Identified a transition from multistep to single-step charge transport as donor/acceptor separation increased.
- Observed coherent, single-step charge transport across 7 or 8 intervening adenine bases.
- Found that coherent transport through DNA is favored across approximately 10 base pairs, correlating with helix delocalization.
Conclusions:
- Coherent charge transport in DNA is a single-step process over specific adenine sequences.
- The observed transport mechanism contrasts with typical molecular wire behavior.
- DNA's helical structure and base stacking play a significant role in facilitating efficient charge transport.
Related Concept Videos
02:05DNA as a Genetic Template
Two structural features of the DNA molecule provide a basis for the mechanisms of heredity: the four nucleotide bases and its double-stranded nature. The Watson-Crick model of double-helical DNA structure, proposed in 1952, drew heavily upon the X-ray crystallography work of researchers Rosalind Franklin and Maurice Wilkins. Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine for their work in 1962. Franklin was, controversially, excluded from the prize for...
02:31Homologous Recombination
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
02:08Gene Conversion
Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
01:32Chromatin Packaging
Each human somatic cell contains 6 billion base pairs of DNA. Each base pair is 0.34 nm long, meaning each diploid cell contains a staggering 2 meters of DNA. This long DNA strand is packed inside a nucleus measuring only 10-20 microns in diameter with the help of specialized DNA-binding proteins called histones. Together they form a compact DNA-protein complex called chromatin. The chromatin is further compacted into higher-order structures. The highest level of compaction is achieved during...
02:04Fixing Double-strand Breaks
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
01:57Sanger Sequencing
DNA sequencing is a fundamental technique that is routinely used in the biological sciences. This method can be applied to a range of questions at different scales - from the sequencing of a cloned DNA fragment or the study of a mutation in a gene up to whole-genome sequencing. However, despite the widespread use of sequencing today, it was not until 1977 that Fredrick Sanger and his collaborators developed the chain-termination method to decode DNA sequences. It relies on the separation of a...