Enantioenrichment by Sublimation of Proteinogenic and Non-Natural Amino Acids as a Plausible Model of Prebiotic Homochirogenesis Доклады на конференциях
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Тип доклада | Устный | ||||
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Origins 2014 [ISSOL - The International Astrobiology Society and Bioastronomy (IAU C51) Joint International Conference] 06-11 июл. 2014 , Nara |
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Реферат:
It is believed that the homochirality of building blocks of life like amino acids (AAs) and sugars (biological systems use just one of two possible mirror isomers) is a prerequisite requirement for the origin and evolution of life. Among different mechanisms that might have triggered the initial disparity in the enantiomeric ratio on the primitive Earth, the key roles were assigned to: (i) local chiral symmetry breaking and (ii) the inflow of extraterrestrial matter (eg the carbonaceous meteorites containing non-racemic AAs).
Recently it has been revealed that sublimation, a subject almost completely neglected for a long time, gives a pathway to enantioenrichment of natural AAs (Tarasevych et al. 2013a and references herein). Starting from a mixture with a low content of an enantiopure AA (Ala, Leu, Phe, Pro, Val), a partial sublimation gives an important enrichment of the sublimate (Bellec and Guillemin 2010; Tarasevych et al 2013a). The resulted disparity in the ratio between enantiomers of a partial sublimate is determined by the crystalline nature of the starting mixture: we observed a drastic difference in the behavior of (i) mixtures based on true racemic compounds and (ii) mechanical mixtures of two enantiopure solid phases.
On the other hand, combination of several phase transitions (crystallization and sublimation) can lead to segregation of enantioenriched fractions starting from racemic composition (equal amounts of both mirror isomers) of sublimable aliphatic AAs (Ala, Leu, Pro, Val) in mixtures with non-volatile enantiopure ones (Asn, Asp, Glu, Ser, Thr) (Tarasevych et al. 2103b). The resulted sense of chirality correlates with the handedness of the non-volatile AAs: the observed changes in enantiomeric ratios clearly demonstrate the preferential homochiral interactions and a tendency of natural amino acids to homochiral self-organization.
These experimental data may shed some light on one of the facets of complex and mysterious preobiotic processes that eventually could have led to the origin of life.
References
Bellec A, Guillemin JC (2010a) A simple explanation of the enhancement or depletion of the enantiomeric excess in the partial sublimation of enantiomerically enriched amino acids. Chem Commun 46:1482-1484
Tarasevych AV, Sorochinsky AE, Kukhar VP, Chollet A, Daniellou R, Guillemin JC (2013a) Partial Sublimation of Enantioenriched Amino Acids at Low Temperature. Is it Coming From the Formation of a Euatmotic Composition of the Gaseous Phase? J Org Chem 78:10530-10533
Tarasevych AV, Sorochinsky AE, Kukhar VP, Guillemin JC (2013b) Deracemization of Amino Acids by Partial Sublimation and via Homochiral Self-Organization. Orig Life Evol Biosph 43:129-135
Библиографическая ссылка:
Tarasevych A.V.
, Guillemin J.
Enantioenrichment by Sublimation of Proteinogenic and Non-Natural Amino Acids as a Plausible Model of Prebiotic Homochirogenesis
Origins 2014 [ISSOL - The International Astrobiology Society and Bioastronomy (IAU C51) Joint International Conference] 06-11 Jul 2014
Enantioenrichment by Sublimation of Proteinogenic and Non-Natural Amino Acids as a Plausible Model of Prebiotic Homochirogenesis
Origins 2014 [ISSOL - The International Astrobiology Society and Bioastronomy (IAU C51) Joint International Conference] 06-11 Jul 2014