Scientists study behaviour of electron linked to molecule's chirality crucial for designing drugs

New Delhi, Aug 28 (PTI) Researchers have for the first time studied how behaviour of an electron in a molecule differs based on chirality -- a property that is crucial for developing effective drugs, among other purposes.

Biological molecules, including those that form proteins and DNA, are said to be chiral, which is crucial in designing drugs that act specifically at the target to produce only the desired treatment effect without causing other physiological changes -- or 'specificity'.

A drug can therefore, be rendered ineffective if its chirality is not in line with that of the molecule it is designed to target.

The researchers, led by those at ETH Zurich in Switzerland, said that little research has been done in how movements of an electron -- which is among the smallest building blocks of an atom -- differ in molecules that are chiral, or have a non-superimposable mirror image of themselves.

Considered a fundamental property of matter, chirality of a molecule reveals its 'handedness' -- right or left. Similar to human hands, molecules in nature can exist in two mirror-image versions -- that is, not entirely identical, despite closely resembling each other. Being chiral means having a non-superimposable mirror image.

The study, published in the journal Nature, is the first to describe a method to manipulate how electrons are being emitted from a chiral molecule, thereby helping visualise and observe electrons' behaviour.

The team used a circularly polarised light -- or light that rotates in a spiral manner resembling a corkscrew. In the first few moments following light hitting a molecule, an electron is emitted.

However, depending on the chirality of the molecule in question and the direction in which the light is rotating, the electron is emitted in the direction in which the light is approaching the molecule or against, the researchers said.

While chirality is perceived as a structural property of a molecule, lead researcher Hans Jakob Wörner, professor of physical chemistry at ETH Zurich, said, "Recently, however, there has been growing evidence that the adoption of the structural approach is not sufficient to fully understand (the) chiral phenomena." The authors added that observing the specific electron behaviour was made possible by a unique device they developed for studying the particles -- it creates circularly polarised pulses for an attosecond, which is a billionth of a billionth of a second.

"Such endeavours have so far been hampered by the lack of characterised circularly polarised attosecond pulses, an obstacle that has recently been overcome," the authors wrote.

This is what is needed to observe electron dynamics on their natural attosecond time scale, they said. PTI KRS NB NB