Phase Transitions of Natural Amino Acids: A Path Towards Homochirality Conference attendances
Language | Английский | ||||
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Participant type | Стендовый | ||||
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Humboldt-Conference “Chemistry and Life” 16-19 May 2013 , Полтава |
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Abstract:
The single chirality of biologically important molecules (amino acids, sugars) is a prerequisite and a requirement for the origin and evolution of life. Among different mechanisms that might have triggered the initial imbalance in the enantiomeric ratio on the Primitive Earth, key roles are assigned (i) to chiral symmetry breaking and (ii) to the inflow of extraterrestrial matter (carbonaceous meteorites containing non-racemic amino acids). The formed small enantiomeric excess can be amplified via phase transitions (crystallization, sublimation) that were proposed as ones of the most probable mechanisms for homochirogenesis [1]. The sublimation, almost uninvestigated subject and forgotten for 30 years, revealed recently a pathway to the enantioenrichment of natural amino acids [2,3]. In the experiments we report here, partial sublimation of a mixture with a low content of an enantiopure amino acid gives a considerable enrichment (Figure 1). Also we shown that deracemisation of racemic aliphatic amino acids AA1 (Ala, Leu, Pro, Val) can be achieved
by a simple sublimation of a presolubiliz-ed solid mixture of the racemates with a less-volatile enantiopure amino acid AA2 (Asn, Asp, Glu, Ser, Thr). The compo-sition of a sublimate consisted of a sca-lemic AA1 is determined by amount of the enantiopure amino acid AA2: (i) an excess of AA2 induces enantioenrichment with the opposite enantiomer (for example, L-AA2 gives D-AA1 enriched sublimates); (ii) sublimation of mixtures with an excess of rac-AA1 leads to the reversal enantio-selectivity (for example, D-AA2 causes D enrichment of AA1 in sublimates) and (iii) using comparable amounts of rac-AA1 and L/D-AA2, an unprecedented stochastic behaviour was revealed. The results present a path to the transfer of enantiopurity between different amino acids. It is noteworthy that just 5 of 22 proteinogenic amino acids are able to homochiral self-organization or in other words to chiral symmetry breaking. On the other side the recent data on enantiomeric composition of the Tagish Lake C2-type carbonaceous meteorite revealed a large enantiomeric excess of aspartic and glutamic acids [4] that we used in our experiments. The relevance of our studies to the Prebiotic Earth and to the evo-lution of the single handedness of biological molecules will be discussed.
References
[1] D.G. Blackmond, Cold Spring Harb. Perspect. Biol. 2010, 2:a002147.
[2] A. Bellec, J.-C. Guillemin, Chem. Comm. 2010, 46,1482-1484.
[3] J. Han, D.J. Nelson, A.E. Sorochinsky, V.A. Soloshonok, Cur. Org. Synth. 2011, 8, 310-317.
Cite:
Tarasevych A.V.
, Kukharʹ V.P.
, Sorochinskij A.E.
, Guillemin J.
Phase Transitions of Natural Amino Acids: A Path Towards Homochirality
Humboldt-Conference “Chemistry and Life” 16-19 May 2013
Phase Transitions of Natural Amino Acids: A Path Towards Homochirality
Humboldt-Conference “Chemistry and Life” 16-19 May 2013