Mechanism of pH-Dependent Photolysis of Aliphatic Amino Acids and Enantiomeric Enrichment of Racemic Leucine by Circularly Polarized Light

Nishino, Hideo; Kosaka, Atsuko; Hembury, Guy A.; Shitomi, Hiroshi; Onuki, Hideo; Inoue, Yoshihisa

doi:10.1021/ol0155788

Cited by 56 publications

(56 citation statements)

References 15 publications

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“…Experimentally, Flores et al (1977) produced ee of up to 2.5% by treating leucine with UV CPL irradiation at 212.8 nm, while Nishino et al (2001) obtained similarly low values and further demonstrated a pH dependence for amino acids' decomposition by CPL, which is highest in acidic conditions, i.e., when both carboxyl and amino groups are protonated. In meteorites, the isovaline ee are nearly 20% and this level of asymmetry would seem to refute the suggestion that UV CPL was its sole causation.…”

Section: Circularly Polarized Lightmentioning

confidence: 89%

Molecular asymmetry in extraterrestrial organic chemistry: An analytical perspective

Pizzarello

Groy

2011

Geochimica et Cosmochimica Acta

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Section: Circularly Polarized Lightmentioning

confidence: 89%

Molecular asymmetry in extraterrestrial organic chemistry: An analytical perspective

Pizzarello

Groy

2011

Geochimica et Cosmochimica Acta

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“…Inoue et al found that the induced ee-values were dependent on the degree of protonation of leucine's carboxylic group, such that pH values close to 1 generated higher anisotropies. The highest ee value obtained was reported to be close to 0.2% [11,41,49].…”

Section: Anisotropy Spectroscopymentioning

confidence: 88%

Anisotropy Spectra for Enantiomeric Differentiation of Biomolecular Building Blocks

Evans

Meinert

Bredehöft

et al. 2013

Topics in Current Chemistry

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All biopolymers are composed of homochiral building blocks, and both D-sugars and L-amino acids uniquely constitute life on Earth. These monomers were originally enantiomerically differentiated under prebiotic conditions. Particular progress has recently been made in support of the photochemical model for this differentiation: the interaction of circularly polarized light with racemic molecules is currently thought to have been the original source for life's biological homochirality. The differential asymmetric photoreactivity of particular small molecules can be characterized by both circular dichroism and anisotropy spectroscopy. Anisotropy spectroscopy, a novel derivative of circular dichroism spectroscopy, records the anisotropy factor g = Δε/ε as a function of the wavelength. Anisotropy spectroscopy promisingly affords the wavelength-dependent determination of the enantiomeric excess (ee) inducible into chiral organic molecules by photochemical irradiation with circularly polarized light. Anisotropy spectra of small molecules therefore provide unique means for characterizing the different photochemical behaviors between enantiomers upon exposure to various wavelengths of circularly polarized light. This chapter will: (1) present the theory and configuration of anisotropy spectroscopy; (2) explain experimentally recorded anisotropy spectra of selected chiral biomolecules such as amino acids; and (3) discuss the relevance of these spectra for the investigation of the origin of the molecular homochirality observed in living organisms. This review describes a new chiroptical technique that is of significance for advances in asymmetric photochemistry and that is also highly relevant for the European Space Agency Rosetta Mission, which will determine enantiomeric excesses (ees) in chiral organic molecules in cometary ices when it lands on Comet 67P/Churyumov-Gerasimenko in November 2014.

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“…Further, extensive attempts of inducing higher ee into chiral molecules have been made in strong acidic solutions at (a) different pH values [74,104], (b) the use of two photon excitation processes [105], and (c) with elliptically polarized light [106], yielding enantiomeric excess ee L values of (a, b) 0.2-0.7% and (c) 3%, respectively, for D,L-leucine. All of these experiments were carried out in aqueous solution, where the optical activity of amino acids arises from the (π*, n) electronic transition of the carboxylic group (chromophore) bound to their α-carbon.…”

Section: Asymmetric Photolysis Of Racemic Organic Moleculesmentioning

confidence: 99%

Photochirogenesis: Photochemical Models on the Origin of Biomolecular Homochirality

et al. 2010

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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 OPEN ACCESS Symmetry 2010, 2 1056 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.

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Mechanism of pH-Dependent Photolysis of Aliphatic Amino Acids and Enantiomeric Enrichment of Racemic Leucine by Circularly Polarized Light

Cited by 56 publications

References 15 publications

Molecular asymmetry in extraterrestrial organic chemistry: An analytical perspective

Molecular asymmetry in extraterrestrial organic chemistry: An analytical perspective

Anisotropy Spectra for Enantiomeric Differentiation of Biomolecular Building Blocks

Photochirogenesis: Photochemical Models on the Origin of Biomolecular Homochirality

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