Uncovering the chiral bias of meteoritic isovaline through asymmetric photochemistry

Bocková, Jana; Jones, Nykola C.; Topin, Jérémie; Hoffmann, Søren Vrønning; Meinert, Cornelia

doi:10.1038/s41467-023-39177-y

Cited by 8 publications

(3 citation statements)

References 67 publications

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“…only an enantiomeric excess (ee) of up to 2.6% could be obtained. Very recently, a similar hypothesis was pursued by Bocková et al to explain a small ee of isoleucine in meteorites [ 66 ]. In these experiments also, enantiomeric excesses of only 2.05% were achieved.…”

Section: The Mystery Of Homochiralitymentioning

confidence: 95%

The Mystery of Homochirality on Earth

Weller

2024

Life

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Homochirality is an obvious feature of life on Earth. On the other hand, extraterrestrial samples contain largely racemic compounds. The same is true for any common organic synthesis. Therefore, it has been a perplexing puzzle for decades how these racemates could have formed enantiomerically enriched fractions as a basis for the origin of homochiral life forms. Numerous hypotheses have been put forward as to how preferentially homochiral molecules could have formed and accumulated on Earth. In this article, it is shown that homochirality of the abiotic organic pool at the time of formation of the first self-replicating molecules is not necessary and not even probable. It is proposed to abandon the notion of a molecular ensemble and to focus on the level of individual molecules. Although the formation of the first self-replicating, most likely homochiral molecule, is a seemingly improbable event, on a closer look, it is almost inevitable that some homochiral molecules have formed simply on a statistical basis. In this case, the non-selective leap to homochirality would be one of the first steps in chemical evolution directly out of a racemic “ocean”. Moreover, most studies focus on the chirality of the primordial monomers with respect to an asymmetric carbon atom. However, any polymer with a minimal size that allows folding to a secondary structure would spontaneously lead to asymmetric higher structures (conformations). Most of the functions of these polymers would be influenced by this inherently asymmetric folding. Furthermore, a concept of physical compartmentalization based on rock nanopores in analogy to nanocavities of digital immunoassays is introduced to suggest that complex cell walls or membranes were also not required for the first steps of chemical evolution. To summarize, simple and universal mechanisms may have led to homochiral self-replicating systems in the context of chemical evolution. A homochiral monomer pool is deemed unnecessary and probably never existed on primordial Earth.

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Section: The Mystery Of Homochiralitymentioning

confidence: 95%

The Mystery of Homochirality on Earth

Weller

2024

Life

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“…One theory regarding the origin of homochirality on earth considers that circularly polarized light (CPL) from the space introduces chiral bias and enantiomeric excess of organics through a photodecomposition pathway [1–4] . It infers the significance of light‐matter interactions of chiral compounds [5–8] .…”

Section: Introductionmentioning

confidence: 99%

Ultrasensitive Solvatochirochromism of Single Benzene Chromophores

Liu,

Hao,

Xing

2024

Chemistry A European J

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Solvents influence the structure, aggregation and folding behaviors of solvatochromic compounds. Ultrasensitive solvent mediated chiroptical response is conducive to the fabrication of molecular platform for sensing and recognition, which however, remains great challenges in conceptual or applicable design. Here we report a cysteine‐based single benzene chromophore system that shows ultrasensitivity to solvents. Compared to the ratiometrically responsive systems, the chiroptical activities could be triggered or inverted depending on the substituents of chiral entities with an ultralow solvent volume fraction (<1 vol%). On drop of dipolar solvents shall significantly induce the emergence or inversion of chiroptical signals in bulky phases. Based on the experimental and computational studies, the ultrasensitivity is contributed to the intimate interplay between solvents and chiral compounds that anchors the specific chiral conformation. It illustrates that structurally simple organic compounds without aggregation or folding behaviors possess pronounced solvatochiroptical properties, which sheds light on the next‐generation of chiroptical sensors and switches.

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“…Moreover, infrared CPL has been detected in the Orion 12 and NGC 6334V 13 star-forming regions, and it is considered to extend into the UV spectral region, the detection of which is hampered by extensive extinction by dust particles. In addition, monochromatic UV CPL irradiation of racemic amino acids [14][15][16][17] as well as achiral inter-/circumstellar ice analogs 18,19 has been shown to lead to the molecular asymmetry in amino acids with an enantiomeric excess (ee) of up to about 5%. 20 The differential absorption of CPL by enantiomers of chiral molecules, so-called circular dichroism (CD), underlies the asymmetric photochemistry likely driving the induction of the chiral bias in space.…”

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confidence: 99%

Chiroptical properties of membrane glycerophospholipids and their chiral backbones

Bocková,

Garcia,

Jones

et al. 2024

Chirality

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Glycerophospholipid membranes are one of the key cellular components. Still, their species‐dependent composition and homochirality remain an elusive subject. In the context of the astrophysical circularly polarized light scenario likely involved in the generation of a chiral bias in meteoritic amino and sugar acids in space, and consequently in the origin of life's homochirality on Earth, this study reports the first measurements of circular dichroism and anisotropy spectra of a selection of glycerophospholipids, their chiral backbones and their analogs. The rather low asymmetry in the interaction of UV/VUV circularly polarized light with sn‐glycerol‐1/3‐phosphate indicates that chiral photons would have been unlikely to directly induce symmetry breaking to membrane lipids. In contrast, the anisotropy spectra of d‐3‐phosphoglyceric acid and d‐glyceraldehyde‐3‐phosphate unveil up to 20 and 100 times higher maximum anisotropy factor values, respectively. This first experimental report, targeted on investigating the origins of phospholipid symmetry breaking, opens up new avenues of research to explore alternative mechanisms leading to membrane lipid homochirality, while providing important clues for the search for chiral biosignatures of extant and/or extinct life in space, in particular for the ExoMars 2028 mission.

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Uncovering the chiral bias of meteoritic isovaline through asymmetric photochemistry

Cited by 8 publications

References 67 publications

The Mystery of Homochirality on Earth

The Mystery of Homochirality on Earth

Ultrasensitive Solvatochirochromism of Single Benzene Chromophores

Chiroptical properties of membrane glycerophospholipids and their chiral backbones

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