Spontaneous mirror symmetry breaking and origin of biological homochirality

Recent reports on both theoretical simulations and on the physical chemistry basis of spontaneous mirror symmetry breaking (SMSB), that is, asymmetric synthesis in the absence of any chiral polarizations other than those arising from the chiral recognition between enantiomers, strongly suggest that the same nonlinear dynamics acting during the crucial stages of abiotic chemical evolution leading to the formation and selection of instructed polymers and replicators, would have led to the homochirality of instructed polymers. We review, in the first instance, which reaction networks lead to the nonlinear kinetics necessary for SMSB, and the thermodynamic features of the systems where this potentiality may be realized. This could aid not only in the understanding of SMSB, but also the design of reliable scenarios in abiotic evolution where biological homochirality could have taken place. Furthermore, when the emergence of biological chirality is assumed to occur during the stages of chemical evolution leading to the selection of polymeric species, one may hypothesize on a tandem track of the decrease of symmetry order towards biological homochirality, and the transition from the simple chemistry of astrophysical scenarios to the complexity of systems chemistry yielding Darwinian evolution.

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Chemical Basis of Biological Homochirality during the Abiotic Evolution Stages on Earth

Symmetry ◽

10.3390/sym11060814 ◽

2019 ◽

Vol 11 (6) ◽

pp. 814 ◽

Cited By ~ 6

Author(s):

Josep M. Ribó ◽

David Hochberg

Keyword(s):

Symmetry Breaking ◽

Chemical Evolution ◽

Mirror Symmetry ◽

Reaction Network ◽

Reaction Networks ◽

Stationary States ◽

Cell Systems ◽

Basic Model ◽

Stochastic Distribution ◽

Non Equilibrium

Spontaneous mirror symmetry breaking (SMSB), a phenomenon leading to non-equilibrium stationary states (NESS) that exhibits biases away from the racemic composition is discussed here in the framework of dissipative reaction networks. Such networks may lead to a metastable racemic non-equilibrium stationary state that transforms into one of two degenerate but stable enantiomeric NESSs. In such a bifurcation scenario, the type of the reaction network, as well the boundary conditions, are similar to those characterizing the currently accepted stages of emergence of replicators and autocatalytic systems. Simple asymmetric inductions by physical chiral forces during previous stages of chemical evolution, for example in astrophysical scenarios, must involve unavoidable racemization processes during the time scales associated with the different stages of chemical evolution. However, residual enantiomeric excesses of such asymmetric inductions suffice to drive the SMSB stochastic distribution of chiral signs into a deterministic distribution. According to these features, we propose that a basic model of the chiral machinery of proto-life would emerge during the formation of proto-cell systems by the convergence of the former enantioselective scenarios.

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Chirality: The Backbone of Chemistry as a Natural Science

Symmetry ◽

10.3390/sym12121982 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1982

Author(s):

Josep M. Ribó

Keyword(s):

Chemical Evolution ◽

Natural Science ◽

Open Systems ◽

Catalytic Synthesis ◽

Darwinian Evolution ◽

Temporal Scales ◽

Atoms And Molecules ◽

Chemical Complexity ◽

Biological Homochirality

Chemistry as a natural science occupies the length and temporal scales ranging between the formation of atoms and molecules as quasi-classical objects, and the formation of proto-life systems showing catalytic synthesis, replication, and the capacity for Darwinian evolution. The role of chiral dissymmetry in the chemical evolution toward life is manifested in how the increase of chemical complexity, from atoms and molecules to complex open systems, accompanies the emergence of biological homochirality toward life. Chemistry should express chirality not only as molecular structural dissymmetry that at the present is described in chemical curricula by quite effective pedagogical arguments, but also as a cosmological phenomenon. This relates to a necessarily better understanding of the boundaries of chemistry with physics and biology.

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Mirror Symmetry Breaking in Liquids and Their Impact on the Development of Homochirality in Abiogenesis: Emerging Proto-RNA as Source of Biochirality?

Symmetry ◽

10.3390/sym12071098 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1098 ◽

Cited By ~ 3

Author(s):

Carsten Tschierske ◽

Christian Dressel

Keyword(s):

Symmetry Breaking ◽

Mirror Symmetry ◽

Liquid Crystalline ◽

Dynamic Network ◽

Stable States ◽

Fluid Systems ◽

Single Process ◽

Local Mirror Symmetry ◽

Rna Formation ◽

Biological Chirality

Recent progress in mirror symmetry breaking and chirality amplification in isotropic liquids and liquid crystalline cubic phases of achiral molecule is reviewed and discussed with respect to its implications for the hypothesis of emergence of biological chirality. It is shown that mirror symmetry breaking takes place in fluid systems where homochiral interactions are preferred over heterochiral and a dynamic network structure leads to chirality synchronization if the enantiomerization barrier is sufficiently low, i.e., that racemization drives the development of uniform chirality. Local mirror symmetry breaking leads to conglomerate formation. Total mirror symmetry breaking requires either a proper phase transitions kinetics or minor chiral fields, leading to stochastic and deterministic homochirality, respectively, associated with an extreme chirality amplification power close to the bifurcation point. These mirror symmetry broken liquids are thermodynamically stable states and considered as possible systems in which uniform biochirality could have emerged. A model is hypothesized, which assumes the emergence of uniform chirality by chirality synchronization in dynamic “helical network fluids” followed by polymerization, fixing the chirality and leading to proto-RNA formation in a single process.

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Spontaneous mirror symmetry breaking in heterocatalytically coupled enantioselective replicators

Chemical Science ◽

10.1039/c6sc02446g ◽

2017 ◽

Vol 8 (1) ◽

pp. 763-769 ◽

Cited By ~ 20

Author(s):

Josep M. Ribó ◽

Joaquim Crusats ◽

Zoubir El-Hachemi ◽

Albert Moyano ◽

David Hochberg

Keyword(s):

Symmetry Breaking ◽

Mirror Symmetry ◽

Chemical Basis ◽

Selection Of

Hypercycles proposed as a chemical basis for the selection of biological replicators may lead to homochirality when fed from achiral resources.

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2,6-Dibromogallates as a new building block for controlling π-stacking, network formation and mirror symmetry breaking

Chemical Communications ◽

10.1039/d1cc01922h ◽

2021 ◽

Author(s):

Ohjin Kwon ◽

Xiaoqian Cai ◽

Azhar Saeed ◽

Feng Liu ◽

Silvio Poppe ◽

...

Keyword(s):

Symmetry Breaking ◽

Building Block ◽

Mirror Symmetry ◽

Network Formation ◽

Network Structures ◽

Π Stacking ◽

Bicontinuous Cubic ◽

Substituted 1 ◽

End Group

Achiral multi-chain (polycatenar) compounds based on the 2,7-diphenyl substituted [1]benzothieno[3,2-b]benzothiophene (BTBT) unit and a 2,6-dibromo-3,4,5-trialkoxybenzoate end group lead to materials forming bicontinuous cubic liquid crystaline phases with helical network structures...

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