Enantiomeric Excesses Induced in Amino Acids by Ultraviolet Circularly Polarized Light Irradiation of Extraterrestrial Ice Analogs: A Possible Source of Asymmetry for Prebiotic Chemistry

Modica, Paola; Meinert, Cornelia; Marcellus, Pierre de; Nahon, Laurent; Meierhenrich, Uwe J.; d’Hendecourt, Louis Le Sergeant

doi:10.1088/0004-637x/788/1/79

Cited by 108 publications

(121 citation statements)

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“…The L-enantiomeric excesses (eeLs) were measured in five of them: a-alanine, 2,3-diaminopropionic acid, 2-aminobutyric acid, valine, and norvaline, with values ranging from eeL = À0.20 % AE 0.14 % to eeL = À2.54 % AE 0.28 %. The results support an astrophysical scenario in which the solar system was formed in a high-mass star-forming region where icy grains were irradiated during the protoplanetary phase by an external source of circularly polarized light of a given helicity, inducing a stereo-specific photochemistry (Modica et al 2014). …”

Section: Definitionsupporting

confidence: 76%

E

2015

Encyclopedia of Astrobiology

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DefinitionThe Earth is the planet on which we live. It is the third planet from the Sun and one of the telluric (small and rocky) planets of our ▶ Solar System. It has a mean radius of 6,371 km and a mean density of 5.515 g cm À3 . It is distinguished from other planets by the presence of ▶ continental crust, oceans, and ▶ life. Its unusually large core and satellite (the Moon) are believed to result from the collision of a Mars-sized body (protoplanet ▶ Theia) about 4.45 Ga ago.

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Section: Definitionsupporting

confidence: 76%

E

2015

Encyclopedia of Astrobiology

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“…Laboratory experiments with UV CPL have demonstrated a slight preferential destruction of one enantiomer, which resulted in relatively small but reversible EE (depending on the direction of the CPL) from an initially racemic mixture of amino acids (39). When performed at low (i.e., interstellar) temperatures, UV CPL is reported to induce EE during the actual synthesis of compounds (42).…”

Section: Discussionmentioning

confidence: 99%

Enantiomer excesses of rare and common sugar derivatives in carbonaceous meteorites

Cooper

Rios

2016

Proc. Natl. Acad. Sci. U.S.A.

123

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Biological polymers such as nucleic acids and proteins are constructed of only one-the D or L-of the two possible nonsuperimposable mirror images (enantiomers) of selected organic compounds. However, before the advent of life, it is generally assumed that chemical reactions produced 50:50 (racemic) mixtures of enantiomers, as evidenced by common abiotic laboratory syntheses. Carbonaceous meteorites contain clues to prebiotic chemistry because they preserve a record of some of the Solar System's earliest (∼4.5 Gy) chemical and physical processes. In multiple carbonaceous meteorites, we show that both rare and common sugar monoacids (aldonic acids) contain significant excesses of the D enantiomer, whereas other (comparable) sugar acids and sugar alcohols are racemic. Although the proposed origins of such excesses are still tentative, the findings imply that meteoritic compounds and/or the processes that operated on meteoritic precursors may have played an ancient role in the enantiomer composition of life's carbohydrate-related biopolymers.carbonaceous meteorites | sugar acids | enantiomer excesses | aldonic acids | polyols T he organic phase of carbonaceous meteorites comprises an insoluble "macromolecular" material (1-3), a complex mixture of largely uncharacterized solvent-extractable compounds (4), as well as discrete (identified) soluble organic compounds such as amino acids (3, 5) nucleobases (6, 7), and sugar derivatives (8). Analyses of this prebiotic organic carbon have been important in understanding its early Solar System synthesis and history: Characteristics of the organic phase suggest that it consists of both products and survivors of interstellar/presolar grain irradiation (9) and subsequent encapsulation and aqueous reactions (10, 11) in asteroids "parent bodies."Several identified meteoritic organic compounds are chiral: They can exist as two nonsuperimposable mirror image compounds called enantiomers, commonly designated D and L. To date, most chiral meteoritic compounds are reported to be racemic mixtures, i.e., their D and L enantiomers are equal in abundance (3). Racemic compounds are expected in nature because typical abiotic synthetic processes are (historically) thought to occur in the absence of asymmetric influences. Racemic mixtures are equated with pristine/uncontaminated abiotic samples when discussing meteoritic compounds. However, some meteoritic amino acids that are rare on Earth, i.e., they are not constituents of proteins and therefore less likely to be contaminants, have been confirmed to contain L enantiomer excesses (EE) (3, 12, 13). The origins of such excesses are unknown.Sugars, aldehydes, or ketones that contain multiple carbon hydroxyl (carbon alcohol) groups, are also chiral and were likely necessary for the origin of life. In the majority of extant biological sugars and derivatives ("polyols"), the D enantiomers are significantly more abundant than the L enantiomers (we will note exceptions in Results and Natural Occurrence of Relevant Sugar Derivatives and Enantiomers)...

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“…a chiral electromagnetic field) vacuum UV photolysis of a racemic mixture of leucine in the solid-state results in the production of an enantiomeric excess of one of the forms of the amino acid (Meierhenrich et al 2005). Moreover, enantiomeric excesses can be detected when amino acids are directly synthesized within an achiral ice mixture under circularly polarized light (CPL), with an enantiomeric excess of up to 2.54% (de Marcellus et al 2011;Modica et al 2014). In this case, the evolution of the ice under VUV light does produce chiral precursors of organic compounds.…”

Section: Interstellar and Cometary Organic Chemistry Simulation Facilmentioning

confidence: 99%

Earth as a Tool for Astrobiology—A European Perspective

et al. 2017

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Scientists use the Earth as a tool for astrobiology by analyzing planetary field analogues (i.e. terrestrial samples and field sites that resemble planetary bodies in our Solar System). In addition, they expose the selected planetary field analogues in simulation chambers to conditions that mimic the ones of planets, moons and Low Earth Orbit (LEO) space conditions, as well as the chemistry occurring in interstellar and cometary ices. This paper reviews the ways the Earth is used by astrobiologists: (i) by conducting planetary field analogue studies to investigate extant life from extreme environments, its metabolisms, adaptation strategies and modern biosignatures; (ii) by conducting planetary field analogue studies to investigate extinct life from the oldest rocks on our planet and its biosignatures; (iii) by exposing terrestrial samples to simulated space or planetary environments and producing a sample analogue to investigate changes in minerals, biosignatures and microorganisms. The European Space Agency (ESA) created a topical team in 2011 to investigate recent activities using the Earth as a tool for astrobiology and to formulate recommendations and scientific needs to improve ground-based astrobiological research. Space is an important tool for astrobiology (see Horneck et al. in Astrobiology, 16:201-243, 2016;Cottin et al., 2017), but access to space is limited. Complementing research on Earth provides fast access, more replications and higher sample throughput. The major conclusions of the topical team and suggestions for the future include more scientifically qualified calls for field campaigns with planetary analogy, and a centralized point of contact at ESA or the EU for the organization of a survey of such expeditions. An improvement of the coordinated logistics, infrastructures and funding system supporting the combination of field work with planetary simulation investigations, as well as an optimization of the scientific return and data processing, data storage and data distribution is also needed. Finally, a coordinated EU or ESA education and outreach program would improve the participation of the public in the astrobiological activities.

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Enantiomeric Excesses Induced in Amino Acids by Ultraviolet Circularly Polarized Light Irradiation of Extraterrestrial Ice Analogs: A Possible Source of Asymmetry for Prebiotic Chemistry

Cited by 108 publications

References 68 publications

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Enantiomer excesses of rare and common sugar derivatives in carbonaceous meteorites

Earth as a Tool for Astrobiology—A European Perspective

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