The Astrophysical Formation of Asymmetric Molecules and the Emergence of a Chiral Bias

Garcia, Adrien D; Meinert, Cornelia; Sugahara, Haruna; Jones, Nykola C.; Hoffmann, Søren Vrønning; Meierhenrich, Uwe J.

doi:10.3390/life9010029

Cited by 39 publications

(33 citation statements)

References 142 publications

(165 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Not only this, the additional processing by circularly polarised UV radiations in such experiments has been reported to result into enantio‐enrichment of synthesized chiral organic molecules. This further supports the enantiomeric excess of life‐supporting amino acids and sugars observed in astrophysical objects …”

Section: Introductionsupporting

confidence: 79%

Extra‐Terrestrial Gas‐Phase Stereoinversion in Amino Acid Leucine: Thermal and Photochemical Channels

Rani

Vikas

2020

ChemPhysChem

View full text Add to dashboard Cite

Enantiomeric‐excess of the left‐handed enantiomer of proteinogenic amino acids has been reported in the meteoritic samples of carbonaceous chondrites. Such chiral‐bias is recently being believed due to the removal of right‐handed enantiomer through its selective destruction by circularly polarized ultraviolet (UV) radiations in interstellar space. The present work through quantum mechanical computations explores various thermal and photochemical channels for stereoinversion in proteinogenic amino acid Leucine, under the gas‐phase conditions akin to different temperature zones of interstellar medium (ISM). A thermochemical and kinetic analysis for the feasibility of the proposed channels is also carried out in different regions of ISM. The initiation of stereoinversion along all the ground‐state thermal channels is found to be restricted by a very high energy barrier which, however, is proposed to be substantially reduced if the initial step proceeds via an excited‐state. This work reveals that the stereoinversion in Leucine is quite feasible in ISM, provided it is initiated photochemically by UV radiations, which are abundant in ISM.

show abstract

Section: Introductionsupporting

confidence: 79%

Extra‐Terrestrial Gas‐Phase Stereoinversion in Amino Acid Leucine: Thermal and Photochemical Channels

Rani

Vikas

2020

ChemPhysChem

View full text Add to dashboard Cite

show abstract

“…2014; Garcia et al. 2019). Laboratory experiments simulating presolar and interstellar environments have shown that slight l ‐ or d ‐enantiomeric enrichments of 0.2–2.5% of several chiral amino acids, including alanine, valine, norvaline, leucine, α‐amino‐ n ‐butyric acid, and 2,3‐diaminopropanoic acid, can be produced directly from interstellar ice analogs for a given direction of UV circularly polarized light (UV CPL), while no amino acid asymmetry was induced with non‐polarized UV light (Modica et al.…”

Section: Resultsmentioning

confidence: 99%

Abundant extraterrestrial amino acids in the primitive CM carbonaceous chondrite Asuka 12236

Glavin

McLain

Dworkin

et al. 2020

Meteorit & Planetary Scien

View full text Add to dashboard Cite

The Asuka (A)-12236 meteorite has recently been classified as a CM carbonaceous chondrite of petrologic type 3.0/2.9 and is among the most primitive CM meteorites studied to date. Here, we report the concentrations, relative distributions, and enantiomeric ratios of amino acids in water extracts of the A-12236 meteorite and another primitive CM chondrite Elephant Moraine (EET) 96029 (CM2.7) determined by ultra-high-performance liquid chromatography time-of-flight mass spectrometry. EET 96029 was highly depleted in amino acids and dominated by glycine, while a wide diversity of two-to six-carbon aliphatic primary amino acids were identified in A-12236, which had a total amino acid abundance of 360 AE 18 nmol g À1 , with most amino acids present without hydrolysis (free). The amino acid concentrations of A-12236 were double those previously measured in the CM2.7 Paris meteorite, consistent with A-12236 being a highly primitive and unheated CM chondrite. The high relative abundance of a-amino acids in A-12236 is consistent with formation by a Strecker-cyanohydrin dominated synthesis during a limited early aqueous alteration phase on the CM meteorite parent body. The presence of predominantly free glycine, a near racemic mixture of alanine (D/L~0.93-0.96), and elevated abundances of several terrestrially rare nonprotein amino acids including a-aminoisobutyric acid (a-AIB) and racemic isovaline indicate that these amino acids in A-12236 are extraterrestrial in origin. Given a lack of evidence for biological amino acid contamination in A-12236, it is possible that some of the Lenantiomeric excesses (L ee~3 4-64%) of the protein amino acids, aspartic and glutamic acids and serine, are indigenous to the meteorite; however, isotopic measurements are needed for confirmation. In contrast to more aqueously altered CMs of petrologic types ≤2.5, no Lisovaline excesses were detected in A-12236. This observation strengthens the hypothesis that extensive parent body aqueous activity is required to produce or amplify the large L-isovaline excesses that cannot be explained solely by exposure to circularly polarized radiation or other chiral symmetry breaking mechanisms prior to incorporation into the asteroid parent body.

show abstract

“…Concerning the synthesis of life's building blocks, Meierhenrich and co-workers showed that exposure of circular polarized light (CPL) in simulated interstellar racemic alanine can induce a chemical imbalance between the formations of L-or D-alanine where the imbalance depends from the wavelength of the incident CPL and sense of rotation [30,31]. Further investigations, performed in simulated conditions, proven that glyceroaldehyde (1, Scheme 1), the first chiral product of the "formose" reaction [32] -one of the chemical pathways for the synthesis of carbohydrates-is present in comets and other space bodies [31]. It is probable that the chemical imbalance between the two possible stereoisomers of 1 occurred before seeding the Earth by asteroids or comets impact [33] creating the conditions for a deracemization before the prebiotic polymerization of peptides and formation of nucleic acids.…”

Section: Prebiotic Scenarios For the Chemical Imbalance Of Amino Acidmentioning

confidence: 99%

Symmetry Breaking of Phospholipids

Buchet¹,

Fiore²

2020

Preprint

View full text Add to dashboard Cite

Either stereo reactants or stereo catalysis from achiral or chiral molecules are prerequisite to obtain pure enantiomeric lipid derivatives. We reviewed a few plausible organic syntheses of phospholipids under prebiotic conditions with a special attention to the starting materials as pro-chiral dihydroxyacetone and dihydroxyacetone phosphate (DHAP), which are the key molecules to break symmetry in phospholipids. The advantages of homochiral membranes compared to those of heterochiral membranes were analysed in term of specific recognition, optimal functions of enzymes, membrane fluidity and topological packing. All biological membranes contain enantiomeric lipids in modern bacteria, eukarya and archaea. The contemporary archaea, comprising of methanogens, halobacteria and thermoacidophiles are living under extreme conditions reminiscent of primitive environment and may indicate the origin of one ancient evolution path of lipid biosynthesis. The analysis of lipid metabolism reveals that all modern cells including archaea synthetize enantiomeric lipid precursors from prochiral DHAP. sn-glycerol-1-phosphate dehydrogenase (G1PDH), usually found in archaea, catalyses the formation of sn-glycerol-1-phosphate (G1P), while sn-glycerol-3-phosphate dehydrogenase (G3PDH) catalyses the formation of sn-glycerol-3-phosphate (G3P) in bacteria and eukarya. The selective enzymatic activity seems to be the main strategy that evolution retained to obtain enantiomeric pure lipids. The occurrence of two genes encoding for G1PDH and G3PDH, served to build up an evolution tree and the basis of our review focusing on the evolution of these two genes. Gene encoding for G3PDH in Eukarya may originate from G3PDH gene found in rare archaea indicating that archaea appeared earlier in the evolution tree than eukarya. Archaea and bacteria evolved probably separately, due to their distinct respective genes coding for G1PDH and G3PDH. The suggested hypothesis is that catalysis of homochiral G1P or G3P from DHAP are more efficient than those leading to racemic G1P and G3P, since there are no enzymes able to synthesize racemic G1P and G3P from DHAP. We propose that G1PDH or G3DPH, which are not “image mirror enzymes” but belonging to distinct family of proteins, emerged separately during evolution. They were probably selected for their efficient catalytic activities during evolution from large libraries of vesicles containing various biopolymers, including amino acids, carbohydrates, nucleic acids, lipids, and meteorite components to induce chemical imbalance.

show abstract

The Astrophysical Formation of Asymmetric Molecules and the Emergence of a Chiral Bias

Cited by 39 publications

References 142 publications

Extra‐Terrestrial Gas‐Phase Stereoinversion in Amino Acid Leucine: Thermal and Photochemical Channels

Extra‐Terrestrial Gas‐Phase Stereoinversion in Amino Acid Leucine: Thermal and Photochemical Channels

Abundant extraterrestrial amino acids in the primitive CM carbonaceous chondrite Asuka 12236

Symmetry Breaking of Phospholipids

Contact Info

Product

Resources

About