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Special Issue "Symmetry of Life and Homochirality"

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A special issue of Symmetry (ISSN 2073-8994).

Deadline for manuscript submissions: closed (28 February 2010)

Special Issue Editor

Guest Editor
Prof. Dr. David Cline

Physics & Astronomy Department, College of Letters & Sciences, UCLA, 3-166 Knudsen Hall, Box 951547, Los Angeles, CA 90095-1547, USA
Website | E-Mail
Interests: astroparticle physics; solar neutrino puzzle and nucleon decay; unique detection of primordial black holes; gamma-ray astronomy

Special Issue Information

Dear Colleagues,

In 1848 L. Pasteur carried out one of the most important experiments in Life Sciences when he transmitted polarized light through a medium with crystal found near a wine producing facility. These crystals were large enough that the individual symmetry (or resolution) of the crystal could be determined. He discovered that these biological materials caused polarized light to have its plane rotated (or optical activity). Two key results come from this experiment:
(a)-Biological materials are built out of 3-dimensional molecules (stereo
(b)-Most of the key molecules in life are either left-handed or D (right-handed)
We now know that 19 of the 20 Amino Acids that make proteins in life are left-handed. This is sometimes called Chiral Symmetry breaking or Homochirality.
In the physical world the concepts of Symmetry and Symmetry breaking are of key importance, while Symmetry principles are key to important physical theories (i.e. Lorentz Invariance and the Theory of Relativity). Asymmetry comes into the nature of the weak force (that drives the energy production in the sun). This depends on a symmetry breaking that leads to a massive particle the Z° with the same properties as the photon of liquid but is 90 proton masses heaver.*
Some Biologists believe that the very existence of life depends on the chiral symmetry breaking or Homochirality; therefore, understanding the origin of this aspect of life could be related to the understanding of the origin of life to some.

*The author was part of the team that in 1983 discovered the Z° particles at Geneva, Switzerland.

Prof. Dr. David Cline
Guest Editor

Published Papers (8 papers)

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Research

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Open AccessArticle Mirror Symmetry Breaking in Helical Polysilanes: Preference between Left and Right of Chemical and Physical Origin
Symmetry 2010, 2(3), 1625-1652; doi:10.3390/sym2031625
Received: 21 February 2010 / Revised: 2 August 2010 / Accepted: 9 August 2010 / Published: 13 August 2010
Cited by 12 | PDF Full-text (1009 KB) | Supplementary Files
Abstract
From elemental particles to human beings, matter is dissymmetric with respect to mirror symmetry. In 1860, Pasteur conjectured that biomolecular handedness— homochirality—may originate from certain inherent dissymmetric forces existing in the universe. Kipping, a pioneer of organosilicon chemistry, was interested in the handedness
[...] Read more.
From elemental particles to human beings, matter is dissymmetric with respect to mirror symmetry. In 1860, Pasteur conjectured that biomolecular handedness— homochirality—may originate from certain inherent dissymmetric forces existing in the universe. Kipping, a pioneer of organosilicon chemistry, was interested in the handedness of sodium chlorate during his early research life. Since Kipping first synthesized several Si-Si bonded oligomers bearing phenyl groups, Si-Si bonded high polymers carrying various organic groups—polysilanes—can be prepared by sodium-mediated condensation of the corresponding organodichlorosilanes. Among these polysilanes, optically active helical polysilanes with enantiomeric pairs of organic side groups may be used for testing the mirror symmetry-breaking hypothesis by weak neutral current (WNC) origin in the realm of chemistry and material science. Several theoretical studies have predicted that WNC-existing chiral molecules with stereogenic centers and/or stereogenic bonds allow for distinguishing between image and mirror image molecules. Based on several amplification mechanisms, theorists claimed that minute differences, though still very subtle, may be detectable by precise spectroscopic and physicochemical measurements if proper chiral molecular pairs were employed. The present paper reports comprehensively an inequality between six pairs of helical polysilane high polymers, presumably, detectable by (chir)optical and achiral 29Si-/13C- NMR spectra, and viscometric measurements. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
Open AccessArticle Experimental Test of L- and D-Amino Acid Binding to L- and D-Codons Suggests that Homochirality and Codon Directionality Emerged with the Genetic Code
Symmetry 2010, 2(2), 1180-1200; doi:10.3390/sym2021180
Received: 9 June 2010 / Revised: 18 June 2010 / Accepted: 22 June 2010 / Published: 23 June 2010
Cited by 2 | PDF Full-text (1010 KB)
Abstract
L-amino acids bind preferentially to their D-codons, but almost nothing is known about whether D-amino acids correspondingly prefer L-codons, or how codon directionality affects amino acid binding. To investigate these issues, two D-RNA-oligonucleotides having inverse base sequences (D-CGUA and D-AUGC) and their corresponding
[...] Read more.
L-amino acids bind preferentially to their D-codons, but almost nothing is known about whether D-amino acids correspondingly prefer L-codons, or how codon directionality affects amino acid binding. To investigate these issues, two D-RNA-oligonucleotides having inverse base sequences (D-CGUA and D-AUGC) and their corresponding L-RNA-oligonucleotides (L-CGUA and L-AUGC) were synthesized and their affinity determined for Gly and eleven pairs of L- and D-amino acids. The data support the hypothesis (Root-Bernstein, Bioessays 2007; 29: 689–698) that homochirality and codon directionality emerged as a function of the origin of the genetic code itself. Further tests involving amplification methods are proposed. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
Open AccessArticle Symmetry versus Asymmetry in the Molecules of Life: Homomeric Protein Assemblies
Symmetry 2010, 2(2), 884-906; doi:10.3390/sym2020884
Received: 27 February 2010 / Revised: 7 April 2010 / Accepted: 12 April 2010 / Published: 19 April 2010
Cited by 4 | PDF Full-text (5914 KB)
Abstract
The essay is dedicated to the relation of symmetry and asymmetry-chirality in Nature. The Introduction defines symmetry and its impact on basic definitions in science and human activities. The following section Chirality of molecules reveals breifly development of notion of chirality and its
[...] Read more.
The essay is dedicated to the relation of symmetry and asymmetry-chirality in Nature. The Introduction defines symmetry and its impact on basic definitions in science and human activities. The following section Chirality of molecules reveals breifly development of notion of chirality and its significance in living organisms and science. Homochirality is a characteristic hallmark of life and its significance is presented in the section Homochirality of Life. Proteins, important constituents of living cells performing versatile functions are chiral macromolecules composed of L-amino acids. In particular, the protein assemblies are of a great importance in functions of a cell. Therefore, they have attracted researches to examine them from different points of view. Among proteins of known three-dimensional structures about 50–80% of them exist as homomeric protein complexes. Protein monomers lack any intrinsic, underlying symmetry, i.e. enantiomorphic protein molecules involve left-handed amino acids but their asymmetry does not appear to extend to the level of quaternary structures (homomeric complexes) as observed by Chothia in 1991. In the section Homomeric assemblies we performed our analysis of very special cases of homomers revealing non-crystallographic symmetry in crystals. Homochiral proteins can crystallize only in enantiomorphic space groups. Among 230 existing space groups 65 are enantiomorphic containing limited symmetry elements that are rotation and screw-rotation axes. Any axis of rotation symmetry of a crystal lattice must be two-fold, three-fold, four-fold, or six-fold. Five-fold, seven-fold, and higher-fold rotation symmetry axes are incompatible with the symmetry under spatial displacement of the three-dimensional crystal lattice. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
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Open AccessArticle Chiroptical Properties of Amino Acids: A Density Functional Theory Study
Symmetry 2010, 2(2), 935-949; doi:10.3390/sym2020934
Received: 6 March 2010 / Revised: 6 April 2010 / Accepted: 14 April 2010 / Published: 19 April 2010
Cited by 10 | PDF Full-text (3114 KB)
Abstract
Amino acids are involved in many scientific theories elucidating possible origins of life on Earth. One of the challenges when discussing the evolutionary origin of biopolymers such as proteins and oligonucleotides in living organisms is the phenomenon that these polymers implement monomers of
[...] Read more.
Amino acids are involved in many scientific theories elucidating possible origins of life on Earth. One of the challenges when discussing the evolutionary origin of biopolymers such as proteins and oligonucleotides in living organisms is the phenomenon that these polymers implement monomers of exclusively one handedness, a feature called biomolecular homochirality. Many attempts have been made to understand this process of racemic symmetry breaking. Assuming an extraterrestrial origin of the molecular building blocks of living organisms, their susceptibility to asymmetric photolysis by the absorption of circularly polarized electromagnetic radiation in interstellar space was proposed. In order to predict whether the interaction of circularly polarized light with various racemic amino acids can induce an enantiomeric excess, we investigated the electronic and chiroptical properties of the amino acids valine and isovaline by a molecular modelling approach based on quantum chemistry (Density Functional Theory). The average spectra of both L-valine and L-isovaline have been produced on the basis of Boltzmann population analysis using computed spectra for the various conformations of each amino acid. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
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Review

Jump to: Research

Open AccessReview Possible Physical Mechanisms in the Galaxy to Cause Homochiral Biomaterials for Life
Symmetry 2010, 2(3), 1450-1460; doi:10.3390/sym2031450
Received: 2 February 2010 / Revised: 8 May 2010 / Accepted: 21 June 2010 / Published: 9 July 2010
Cited by 1 | PDF Full-text (438 KB)
Abstract The origin of homochirality in life remains a mystery that some believe is essential for life, and which may result from chiral symmetry breaking interactions with galactic organic material. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
Open AccessReview Photochirogenesis: Photochemical Models on the Origin of Biomolecular Homochirality
Symmetry 2010, 2(2), 1055-1080; doi:10.3390/sym2021055
Received: 1 March 2010 / Revised: 26 April 2010 / Accepted: 13 May 2010 / Published: 25 May 2010
Cited by 11 | PDF Full-text (557 KB)
Abstract
Current research focuses on a better understanding of the origin of biomolecular asymmetry by the identification and detection of the possibly first chiral molecules that were involved in the appearance and evolution of life on Earth. We have reasons to assume that these
[...] Read more.
Current research focuses on a better understanding of the origin of biomolecular asymmetry by the identification and detection of the possibly first chiral molecules that were involved in the appearance and evolution of life on Earth. We have reasons to assume that these molecules were specific chiral amino acids. Chiral amino acids have been identified in both chondritic meteorites and simulated interstellar ices. Present research reasons that circularly polarized electromagnetic radiation was identified in interstellar environments and an asymmetric interstellar photon-molecule interaction might have triggered biomolecular symmetry breaking. We review on the possible prebiotic interaction of ‘chiral photons’ in the form of circularly polarized light, with early chiral organic molecules. We will highlight recent studies on enantioselective photolysis of racemic amino acids by circularly polarized light and experiments on the asymmetric photochemical synthesis of amino acids from only one C and one N containing molecules by simulating interstellar environments. Both approaches are based on circular dichroic transitions of amino acids that will be presented as well. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
Open AccessReview Origin of Homochirality of Amino Acids in the Biosphere
Symmetry 2010, 2(2), 1022-1032; doi:10.3390/sym2021022
Received: 21 January 2010 / Revised: 28 April 2010 / Accepted: 10 May 2010 / Published: 13 May 2010
Cited by 9 | PDF Full-text (1045 KB) | Supplementary Files
Abstract
Discussions are made concerning realistic mechanisms for the origin of L-amino acids in the biosphere. As the most plausible mechanism, it is proposed that a mixture of racemic amino acids in the prebiotic sea caused spontaneous and effective optical resolution through self crystallization,
[...] Read more.
Discussions are made concerning realistic mechanisms for the origin of L-amino acids in the biosphere. As the most plausible mechanism, it is proposed that a mixture of racemic amino acids in the prebiotic sea caused spontaneous and effective optical resolution through self crystallization, even if asymmetric synthesis of a single amino acid has never occurred without the aid of an optically active molecule. This hypothesis is based on recrystallization of a mixture of D,L-amino acids in the presence of excess of D,L-asparagine (Asn). The enantiomeric excess (ee) of each amino acid in the resulting crystals indicates that crystallization of co-existing amino acids with the configuration same as that of Asn took place, although it was incidental whether the enrichment occurred in L- or D-amino acids. In addition, the resulting ee was sufficiently high (up to 100%) to account for the predominance of L-amino acids on the earth. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)
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Open AccessReview The Role of Stochastic Models in Interpreting the Origins of Biological Chirality
Symmetry 2010, 2(2), 767-798; doi:10.3390/sym2020767
Received: 1 March 2010 / Revised: 29 March 2010 / Accepted: 6 April 2010 / Published: 12 April 2010
Cited by 31 | PDF Full-text (590 KB)
Abstract
This review summarizes recent stochastic modeling efforts in the theoretical research aimed at interpreting the origins of biological chirality. Stochastic kinetic models, especially those based on the continuous time discrete state approach, have great potential in modeling absolute asymmetric reactions, experimental examples of
[...] Read more.
This review summarizes recent stochastic modeling efforts in the theoretical research aimed at interpreting the origins of biological chirality. Stochastic kinetic models, especially those based on the continuous time discrete state approach, have great potential in modeling absolute asymmetric reactions, experimental examples of which have been reported in the past decade. An overview of the relevant mathematical background is given and several examples are presented to show how the significant numerical problems characteristic of the use of stochastic models can be overcome by non-trivial, but elementary algebra. In these stochastic models, a particulate view of matter is used rather than the concentration-based view of traditional chemical kinetics using continuous functions to describe the properties system. This has the advantage of giving adequate description of single-molecule events, which were probably important in the origin of biological chirality. The presented models can interpret and predict the random distribution of enantiomeric excess among repetitive experiments, which is the most striking feature of absolute asymmetric reactions. It is argued that the use of the stochastic kinetic approach should be much more widespread in the relevant literature. Full article
(This article belongs to the Special Issue Symmetry of Life and Homochirality)

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