Structure and Reactivity in Langmuir Films of Amphiphilic Alkyl and Thio-alkyl Esters of α-Amino Acids at the Air/Water Interface

Eliash, Ran; Weissbuch, Isabelle; Weygand, M.; Kjær, Kristian; Leiserowitz, Leslie; Lahav, Meir

doi:10.1021/jp049381j

Cited by 20 publications

(27 citation statements)

References 24 publications

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“…In this work, there is no disruption of the surface film during analysis, a problem faced in the collection procedures in previous studies of long-chain amino acid esters (27)(28)(29). We thereby demonstrate unambiguously that the chemistry occurred at the air-water interface.…”

Section: Resultsmentioning

confidence: 53%

“…We thereby demonstrate unambiguously that the chemistry occurred at the air-water interface. The long-chain amino acids used previously (27)(28)(29) were also highly synthetic molecules, which were unlikely to have been readily available on early Earth. Here, a two-carbonlong amino acid ester is used as a more plausible model for the initial abiotic peptide bond formation reactions because it contains a much smaller activation group and is also water-soluble.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, in these previous studies (27-29) the reactants were insoluble and their concentration was limited by the monolayer, which is deposited only at the surface. There is some debate in the literature as to whether the long-chain amino acid esters are capable of forming any peptides more than two monomers long (29) because of the confined nature of the surface film. Here, this problem is eliminated because there is a constant supply of monomers available for reaction adsorbing to the interface from the bulk solution, analogous to the reservoir of monomers provided by the ocean on early Earth.…”

Section: Resultsmentioning

confidence: 99%

“…Reaction amongst the surface monomers was promoted in these studies (27)(28)(29) through surface compression, and supported by subsequent collection, drying, and analysis of the surface products. In the work presented here, infrared reflection absorption spectroscopy (IRRAS) and Langmuir trough methods were used to observe, in situ, complex formation with a metal cation followed by condensation chemistry leading to peptide bond formation occurring at the air-water interface.…”

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confidence: 80%

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In situ observation of peptide bond formation at the water–air interface

Griffith

Vaida

2012

Proc. Natl. Acad. Sci. U.S.A.

146

155

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We report unambiguous spectroscopic evidence of peptide bond formation at the air-water interface, yielding a possible mechanism providing insight into the formation of modern ribosomal peptide bonds, and a means for the emergence of peptides on early Earth. Protein synthesis in aqueous environments, facilitated by sequential amino acid condensation forming peptides, is a ubiquitous process in modern biology, and a fundamental reaction necessary in prebiotic chemistry. Such reactions, however, are condensation reactions, requiring the elimination of a water molecule for every peptide bond formed, and are thus unfavorable in aqueous environments both from a thermodynamic and kinetic point of view. We use the hydrophobic environment of the air-water interface as a favorable venue for peptide bond synthesis, and demonstrate the occurrence of this chemistry with in situ techniques using Langmuir-trough methods and infrared reflection absorption spectroscopy. Leucine ethyl ester (a small amino acid ester) first partitions to the water surface, then coordinates with Cu 2þ ions at the interface, and subsequently undergoes a condensation reaction selectively forming peptide bonds at the air-water interface.

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Section: Resultsmentioning

confidence: 53%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 80%

See 2 more Smart Citations

In situ observation of peptide bond formation at the water–air interface

Griffith

Vaida

2012

Proc. Natl. Acad. Sci. U.S.A.

146

155

View full text Add to dashboard Cite

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“…However, more recent reinvestigations of these reactions, using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS) of the products, with racemic monomers where one enantiomer was tagged with deuterium atoms, showed that the formed peptides are no longer than dipeptides [30]. For this reason, such esters cannot be regarded as realistic prebiotic model systems in the formation of long oligopeptides.…”

Section: Isotactic Oligomers Generated Within Monolayers At the Air-wmentioning

confidence: 99%

“Absolute” Asymmetric Polymerization within Crystalline Architectures: Relevance to the Origin of Homochirality

Weissbuch

Lahav

2012

Materials Science and Technology

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The emergence of the homochiral proteins and nucleic acids, composed from residues of L-amino acids and D-sugars respectively, from the achiral prebiotic world still provides an unsolved conundrum in the field of the origin of life. This mist results from the fundamental symmetry rules as defined, at the end of the nineteenth century, by the Curie principle [1], which states that, '' . . . a physical event cannot have a symmetry lower than that of the event that caused it.''There are two classes of asymmetric transformation, which are in keeping with this symmetry rule. In the first class, chiral reactants are converted, via chemical reactions, into chiral products; in the second class, ''mirror-symmetry'' can be broken spontaneously in either a single or a small number of chemical reactions. In a large number of related independent events, however, the system will preserve its initial nonchiral symmetry. Such class of stochastic asymmetric transformations might have been relevant to chiro-biogenesis, provided the scenario can be accepted that life started in a small number of locations, and that the handedness generated by chance has been amplified and propagated during a competition with heterochiral architectures, such that one of the homochiral architectures has tripped and the other has won the rivalry [2][3][4][5].In this chapter, the second class of stochastic asymmetric synthesis of polymers -referred to as ''absolute'' asymmetric synthesis -and which has been materialized in laboratory experiments, is described. Several successful systems of ''mirror-symmetry breaking'' have been shown to comprise the following steps: spontaneous self-assembly of molecules into crystalline-like supramolecular architectures that create a local homochiral molecular environment exerting asymmetric induction in the ensuing propagation of the polymerization reaction. Farina [6] coined the term ''through-space'' asymmetric transformations in order to distinguish them from the common ''through-bond'' reactions.Here, attention is confined especially to the asymmetric transformations of achiral monomers within crystalline or quasi-crystalline architectures. In particular, the early studies of asymmetric polymerizations performed within enantiomorphous

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