Did X-rays in space 'kick start' biological molecules?
6 Dec 2008
Molecules in nature can come in two different, mirror image types or 'chiralities'. The basic molecules that make up all living things, however, have a predetermined chirality or 'handedness,' similar to the way people are right- or left-handed. This chirality has a profound influence on the chemistry and molecular interactions of living organisms.
Just why a preference for one chirality should have developed from the elementary building blocks of matter has long been one of the great mysteries of the origin of life. Now, scientists at the US Department of Energy's Argonne National Laboratory have found part of the answer by discovering a way to induce this preferential handedness in pre-biological molecules.
'Understanding how the molecules necessary for life originated is one of the most basic scientific questions in biochemistry,' Argonne chemist Richard Rosenberg said. 'Chirality plays a fundamental role in biological processes and researchers have been trying to discover the mechanisms that led to this property for years.'
< Argonne chemist Richard Rosenberg found that a combination of magnetism and X-rays can produce one kind of molecule over another.
Rosenberg used X-rays from the Advanced Photon Source facility to bombard molecules fixed to a magnetic substrate, and X-ray photoelectron spectroscopy to see changes in the bonds holding those molecules together.
He found that changing the direction of the magnetisation in relation to the X-ray beam created in the molecules an excess of one 'handedness' over another. Changing the magnetisation direction reverses the spin polarisation of the secondary, or low-energy, electrons emitted from substances.
Based on the these results, it is conceivable that chirality could have been introduced by X-ray irradiation of molecules as they travelled through space while stuck on magnetised substances in dust clouds, meteors, comets or on primitive planets.
Iron, for instance, is a common element and is magnetic in many forms, while X-rays, other ionising radiation and magnetic fields are prevalent throughout the universe.
Adapted from information issued by The US Department of Energy's Argonne National Laboratory.
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