filmov
tv
Goldschmidt2023 Plenary by Cornelia Meinert
Показать описание
Why nature never makes chiral twins – insights from cometary ice analogues and extra-terrestrial sample analyses
‘How did life choose its handedness?’ While amino acids and sugars can exist in left- or right-handed forms, life on Earth predominantly uses left-handed amino acids and right-handed sugars. This homochirality is necessary for building functional proteins and RNA/DNA, but the reason for this preference remains unclear. Some evidence suggests that the asymmetric interaction of chiral organics with stellar ultraviolet circularly polarized light (UV CPL) may be responsible (Fig. 1)1. The astrophysical origin of homochirality is strengthened by i) the detection of l-enriched amino and d-enriched sugar acids in meteoritic samples2, ii) the detection of CPL in star-forming regions3, and iii) experiments studying the interaction of UV CPL with prebiotic chiral species4. I will therefore highlight a few significant results on our on-going cometary ice simulation experiments5, newly recorded anisotropy spectra as a key tool to decipher the response of chiral molecules to UV CPL6 and present future strategies towards furthering understanding the origin of asymmetric prebiotic molecules. Moreover, I will present our major findings on recent asymmetric photolysis experiments using laser and synchrotron CPL sources to critically discuss whether stellar UV CPL could have induced a common chiral bias across molecular families. These will be complemented by long-awaited first asymmetric photolysis experiments on isovaline using our newly built tunable laser set-up.
‘How did life choose its handedness?’ While amino acids and sugars can exist in left- or right-handed forms, life on Earth predominantly uses left-handed amino acids and right-handed sugars. This homochirality is necessary for building functional proteins and RNA/DNA, but the reason for this preference remains unclear. Some evidence suggests that the asymmetric interaction of chiral organics with stellar ultraviolet circularly polarized light (UV CPL) may be responsible (Fig. 1)1. The astrophysical origin of homochirality is strengthened by i) the detection of l-enriched amino and d-enriched sugar acids in meteoritic samples2, ii) the detection of CPL in star-forming regions3, and iii) experiments studying the interaction of UV CPL with prebiotic chiral species4. I will therefore highlight a few significant results on our on-going cometary ice simulation experiments5, newly recorded anisotropy spectra as a key tool to decipher the response of chiral molecules to UV CPL6 and present future strategies towards furthering understanding the origin of asymmetric prebiotic molecules. Moreover, I will present our major findings on recent asymmetric photolysis experiments using laser and synchrotron CPL sources to critically discuss whether stellar UV CPL could have induced a common chiral bias across molecular families. These will be complemented by long-awaited first asymmetric photolysis experiments on isovaline using our newly built tunable laser set-up.