Nav: Home

Chirality in 'real-time'

January 10, 2019

In nature, certain molecules with the same chemical composition, can exist in two different shapes that are mirrors images of each other, much like our hands. This property is known as "chirality" and molecules with different chirality are called enantiomers. Enantiomers can exhibit entirely different chemical or biological properties, and separating them is a major issue in drug development and in medicine.

The method commonly used to detect enantiomers is circular dichroism (CD) spectroscopy. It exploits the fact that light polarized into a circular wave (like a whirlpool) is absorbed differently by left-handed and right-handed enantiomers. Steady-state CD spectroscopy is a major structural tool in (bio)chemical analysis.

During their function, biomolecules undergo structural changes that affect their chiral properties. Probing these in real-time (i.e. between 1 picosecond and 1 nanosecond) provides a view of their biological function, but this has been challenging in the deep-UV spectrum (wavelengths below 300 nm) where most biologically relevant molecules such as amino acids, DNA and peptide helices absorb light.

The limitations are due to the lack of adequate sources of pulsed light and of sensitive detection schemes. But now, the group of Majed Chergui at the Lausanne Centre for Ultrafast Science (EPFL) has developed a setup that allows the visualization of the chiral response of (bio)molecules by CD spectroscopy with a resolution of 0.5 picoseconds.

The setup uses a photoelastic modulator, which is an optical device that can control the polarization of light. In this system, the modulator permits shot-to-shot polarization switching of a 20 kHz femtosecond pulse train in the deep-UV range (250-370 nm). It is then possible to record changes in the chirality of molecules at variable time-delays after they are excited with a short laser pulse.

"Amino acid residues and DNA bases absorb light below 300 nm," says Malte Oppermann, the paper's first author. "This set-up is the first to cover this region, and we successfully tested it on a model molecular system. Our next aim is to move on to larger biosystems, like DNA oligomers."
Other contributors

University of Geneva
University of Zurich


Malte Oppermann, Benjamin Bauer, Thomas Rossi, Francesco Zinna, Jan Helbing, Jérôme Lacour, Majed Chergui. Ultrafast broadband circular dichroism in the deep ultraviolet. Optica 6(1): 56-60, 10 January 2019. DOI: 10.1364/OPTICA.6.000056

Ecole Polytechnique Fédérale de Lausanne

Related Dna Articles:

Penn State DNA ladders: Inexpensive molecular rulers for DNA research
New license-free tools will allow researchers to estimate the size of DNA fragments for a fraction of the cost of currently available methods.
It is easier for a DNA knot...
How can long DNA filaments, which have convoluted and highly knotted structure, manage to pass through the tiny pores of biological systems?
How do metals interact with DNA?
Since a couple of decades, metal-containing drugs have been successfully used to fight against certain types of cancer.
Electrons use DNA like a wire for signaling DNA replication
A Caltech-led study has shown that the electrical wire-like behavior of DNA is involved in the molecule's replication.
Switched-on DNA
DNA, the stuff of life, may very well also pack quite the jolt for engineers trying to advance the development of tiny, low-cost electronic devices.
Researchers are first to see DNA 'blink'
Northwestern University biomedical engineers have developed imaging technology that is the first to see DNA 'blink,' or fluoresce.
Finding our way around DNA
A Salk team developed a tool that maps functional areas of the genome to better understand disease.
A 'strand' of DNA as never before
In a carefully designed polymer, researchers at the Institute of Physical Chemistry of the Polish Academy of Sciences have imprinted a sequence of a single strand of DNA.
Doubling down on DNA
The African clawed frog X. laevis genome contains two full sets of chromosomes from two extinct ancestors.
'Poring over' DNA
Church's team at Harvard's Wyss Institute for Biologically Inspired Engineering and the Harvard Medical School developed a new electronic DNA sequencing platform based on biologically engineered nanopores that could help overcome present limitations.

Related Dna Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...