Amino acid gas phase circular dichroism and implications for the origin of biomolecular asymmetry

• Published in: Nature communications 2022-01, Vol.13 (1), p.502-502, Article 502
• Main Authors: Meinert, Cornelia, Garcia, Adrien D., Topin, Jérémie, Jones, Nykola C., Diekmann, Mira, Berger, Robert, Nahon, Laurent, Hoffmann, Søren V., Meierhenrich, Uwe J.
• Format: Article
• Language: English
• Subjects: 119/118; 639/638/439; 639/638/440/527/873; 639/638/563/606; 639/638/904; Amino acids; Amino Acids - chemistry; Analytical chemistry; Anisotropy; Astrophysics; Asymmetry; Broken symmetry; Charge distribution; Chemical Physics; Chemical Sciences; Circular dichroism; Circular Dichroism - methods; Circular polarization; Comets; Computational Chemistry; Dichroism; Gases - chemistry; Glycine; Humanities and Social Sciences; Interstellar gas; Life cycles; multidisciplinary; or physical chemistry; Origin of Life; Photochemical reactions; Photochemicals; Photochemistry; Physics; Polarized light; Radiation; Science; Science (multidisciplinary); Sciences of the Universe; Stereoisomerism; Symmetry; Synchrotron radiation; Synchrotrons; Theoretical and; Vapor phases; Vapor pressure
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-28184-0

Life on Earth employs chiral amino acids in stereochemical l -form, but the cause of molecular symmetry breaking remains unknown. Chiroptical properties of amino acids – expressed in circular dichroism (CD) – have been previously investigated in solid and solution phase. However, both environments distort the intrinsic charge distribution associated with CD transitions. Here we report on CD and anisotropy spectra of amino acids recorded in the gas phase, where any asymmetry is solely determined by the genuine electromagnetic transition moments. Using a pressure- and temperature-controlled gas cell coupled to a synchrotron radiation CD spectropolarimeter, we found CD active transitions and anisotropies in the 130–280 nm range, which are rationalized by ab initio calculation. As gas phase glycine was found in a cometary coma, our data may provide insights into gas phase asymmetric photochemical reactions in the life cycle of interstellar gas and dust, at the origin of the enantiomeric selection of life’s l -amino acids. Chiroptical properties of amino acids are challenging to investigate in the gas phase due to the low vapor pressure of these molecules. Here the authors succeed in measuring circular dichroism active transitions and anisotropies in the ultraviolet range for several gas-phase amino acids, shedding light on the interactions between molecules and circularly polarized light that lead to chiral symmetry breaking.