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Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles

Replicators are fundamental to the origin of life and evolvability. Biology exhibits homochirality: only one of two enantiomers is used in proteins and nucleic acids. Thermodynamic studies of chemical replicators able to lead to homochirality shed valuable light on the origin of homochirality and li...

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Autores principales: Hochberg, David, Ribó, Josep M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6463124/
https://www.ncbi.nlm.nih.gov/pubmed/30884765
http://dx.doi.org/10.3390/life9010028
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author Hochberg, David
Ribó, Josep M.
author_facet Hochberg, David
Ribó, Josep M.
author_sort Hochberg, David
collection PubMed
description Replicators are fundamental to the origin of life and evolvability. Biology exhibits homochirality: only one of two enantiomers is used in proteins and nucleic acids. Thermodynamic studies of chemical replicators able to lead to homochirality shed valuable light on the origin of homochirality and life in conformity with the underlying mechanisms and constraints. In line with this framework, enantioselective hypercyclic replicators may lead to spontaneous mirror symmetry breaking (SMSB) without the need for additional heterochiral inhibition reactions, which can be an obstacle for the emergence of evolutionary selection properties. We analyze the entropy production of a two-replicator system subject to homochiral cross-catalysis which can undergo SMSB in an open-flow reactor. The entropy exchange with the environment is provided by the input and output matter flows, and is essential for balancing the entropy production at the non-equilibrium stationary states. The partial entropy contributions, associated with the individual elementary flux modes, as defined by stoichiometric network analysis (SNA), describe how the system’s internal currents evolve, maintaining the balance between entropy production and exchange, while minimizing the entropy production after the symmetry breaking transition. We validate the General Evolution Criterion, stating that the change in the chemical affinities proceeds in a way as to lower the value of the entropy production.
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spelling pubmed-64631242019-04-22 Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles Hochberg, David Ribó, Josep M. Life (Basel) Article Replicators are fundamental to the origin of life and evolvability. Biology exhibits homochirality: only one of two enantiomers is used in proteins and nucleic acids. Thermodynamic studies of chemical replicators able to lead to homochirality shed valuable light on the origin of homochirality and life in conformity with the underlying mechanisms and constraints. In line with this framework, enantioselective hypercyclic replicators may lead to spontaneous mirror symmetry breaking (SMSB) without the need for additional heterochiral inhibition reactions, which can be an obstacle for the emergence of evolutionary selection properties. We analyze the entropy production of a two-replicator system subject to homochiral cross-catalysis which can undergo SMSB in an open-flow reactor. The entropy exchange with the environment is provided by the input and output matter flows, and is essential for balancing the entropy production at the non-equilibrium stationary states. The partial entropy contributions, associated with the individual elementary flux modes, as defined by stoichiometric network analysis (SNA), describe how the system’s internal currents evolve, maintaining the balance between entropy production and exchange, while minimizing the entropy production after the symmetry breaking transition. We validate the General Evolution Criterion, stating that the change in the chemical affinities proceeds in a way as to lower the value of the entropy production. MDPI 2019-03-15 /pmc/articles/PMC6463124/ /pubmed/30884765 http://dx.doi.org/10.3390/life9010028 Text en © 2019 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) ).
spellingShingle Article
Hochberg, David
Ribó, Josep M.
Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title_full Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title_fullStr Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title_full_unstemmed Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title_short Entropic Analysis of Mirror Symmetry Breaking in Chiral Hypercycles
title_sort entropic analysis of mirror symmetry breaking in chiral hypercycles
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6463124/
https://www.ncbi.nlm.nih.gov/pubmed/30884765
http://dx.doi.org/10.3390/life9010028
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