Carbonyl Sulfide-Mediated Prebiotic Formation of Peptides

Leman, Luke J.; Orgel, Leslie E.; Ghadiri, Mojtaba

doi:10.1126/science.1102722

Cited by 388 publications

(312 citation statements)

References 11 publications

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“…The formation of dipeptides could reasonably be considered a simple evolutionary step for prebiotic amino acids to undertake on the early Earth, for example, by the facile reaction between amino acids and carbonyl sulfide near volcanic sources (25). On the other hand, the step should also be expected to be stochastic in the distribution of homochiral and racemic peptide products.…”

Section: Resultsmentioning

confidence: 99%

The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution

Weber

Pizzarello

2006

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

116

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Using a water-based prebiotic model of sugar synthesis involving glycolaldehyde self-condensation, we demonstrate that homochiral L-dipeptide catalysts lead to the stereospecific syntheses of tetroses. The asymmetric effect is largest for erythrose, which may reach a D-enantiomeric excess of >80% with L-Val-L-Val catalyst. Based on results obtained with various peptides, we propose a possible catalytic-reaction intermediate, consisting of an imidazolidinone ring formed between the two nitrogen atoms of the peptide catalyst and the C1 of one glycolaldehyde molecule. The study was motivated by the premise that exogenous material, such as the nonracemic amino acids found in meteorites, could have participated in the terrestrial evolution of molecular asymmetry by stereospecific catalysis. Because peptides might have formed readily on the early Earth, it is possible that their catalytic contribution was relevant in the prebiotic processes that preceded the onset of life.prebiotic chemistry ͉ chirality ͉ catalysis A lthough the chemical environments that led to life's origin on the Earth are unknown, our knowledge of current and extinct life processes allows us to postulate some possible working assumptions. For example, we may describe life as an autocatalytic chemical process where simple molecules, such as amino acids and nucleotides, assemble into larger proteins and nucleic acids that, in turn, control their metabolism and synthesis (1). In these terms, we may also identify key requirements that make such processes possible. One such prerequisite is the exclusive one-handedness of the chiral constituents of proteins and nucleotides (L-amino acids and D-sugars) that is essential to extant biopolymers' structure and function and whose origin is unknown.Several general theories have been brought forward in regard to the origin of this terrestrial homochirality (2). Some propose that life first arose from a racemic environment and later evolved to chiral homogeneity; this ''biotic'' premise circumvents the ease with which prebiotic amino acids and sugars would have lost any incremental gain in asymmetry to racemization. Abiotic theories, on the other hand, propose that some asymmetry preceded the onset of life, overcame racemization, and contributed to homochirality. The finding in meteorites of amino acids resistant to racemization and displaying enantiomeric excesses (ee) that, if less extensive, have the same sign (L-) as in terrestrial amino acids (3, 4) supports, albeit does not prove, the latter hypothesis.Apart from either hypothesis, because abiotic syntheses of chiral molecules would produce only racemic mixtures if unaided by catalysts and meteorites' composition shows that any preexisting ee available for the formation of biomolecules would not have been large (4), it is reasonable to assume that the development of chiral homogeneity was an evolutionary process that involved catalysis. This inference, in turn, leads to the question of whether the unique nonracemic amino acids of meteorites might have play...

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Section: Resultsmentioning

confidence: 99%

The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution

Weber

Pizzarello

2006

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

116

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“…Carbonyl sulfide (COS) is a reactive compound that has been detected in volcanic gas and mineral ash (Rasmussen et al 1982), along with its chemical relatives, carbon disulfide and carbon dioxide. Leman et al (2004) found that if COS is present in an aqueous solution of amino acids, di-and tripeptides are synthesized with yields up to 80%. In a second paper, Leman et al (2006) reported that amino-acyl phosphate anhydrides up to 30% yields were synthesized in mixtures of amino acids, phosphate, and COS.…”

Section: Carbonyl Sulfide As a Plausible Prebiotic Condensing Agentmentioning

confidence: 99%

Bioenergetics and Life's Origins

Deamer¹,

Weber²

2010

Cold Spring Harbor Perspectives in Biology

151

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Bioenergetics is central to our understanding of living systems, yet has attracted relatively little attention in origins of life research. This article focuses on energy resources available to drive primitive metabolism and the synthesis of polymers that could be incorporated into molecular systems having properties associated with the living state. The compartmented systems are referred to as protocells, each different from all the rest and representing a kind of natural experiment. The origin of life was marked when a rare few protocells happened to have the ability to capture energy from the environment to initiate catalyzed heterotrophic growth directed by heritable genetic information in the polymers. This article examines potential sources of energy available to protocells, and mechanisms by which the energy could be used to drive polymer synthesis.P revious research on life's origins has for the most part focused on the chemistry and energy sources required to produce the small molecules of life-amino acids, nucleobases, and amphiphiles-and to a lesser extent on condensation reactions by which the monomers can be linked into biologically relevant polymers. In modern living cells, polymers are synthesized from activated monomers such as the nucleoside triphosphates used by DNA and RNA polymerases, and the tRNA-amino acyl conjugates that supply ribosomes with activated amino acids. Activated monomers are essential because polymerization reactions occur in an aqueous medium and are therefore energetically uphill in the absence of activation.A central problem therefore concerns mechanisms by which prebiotic monomers could have been activated to assemble into polymers. Most biopolymers of life are synthesized when the equivalent of a water molecule is removed to form the ester bonds of nucleic acids, glycoside bonds of polysaccharides, and peptide bonds in proteins. In life today, the removal of water is performed upstream of the actual bond formation. This process involves the energetically downhill transfer of electrons, which is coupled to either substrate-level oxidation or generation of a proton gradient that in turn is the energy source for the synthesis of anhydride pyrophosphate bonds in ATP. The energy stored in the pyrophosphate bond is then distributed throughout the cell to drive most other energydependent reactions. This is a complex and highly evolved process, so here we consider simpler ways in which energy could have been

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“…The most commonly cited potential prebiotic activations of stable amino acid derivatives lead to the formation of N −carboxyanhydrides of α-amino acids [12,30,40]. NCAs have several features that make them highly amenable to building a desirable prebiotic chemistry (i.e.…”

Section: The Modelmentioning

confidence: 99%

Toward Homochiral Protocells in Noncatalytic Peptide Systems

Gleiser

Walker

2009

Orig Life Evol Biosph

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The activation-polymerization-epimerization-depolymerization (APED) model of Plasson et al. has recently been proposed as a mechanism for the evolution of homochirality on prebiotic Earth. The dynamics of the APED model in two-dimensional spatially-extended systems is investigated for various realistic reaction parameters. It is found that the APED system allows for the formation of isolated homochiral proto-domains surrounded by a racemate. A diffusive slowdown of the APED network induced, for example, through tidal motion or evaporating pools and lagoons leads to the stabilization of homochiral bounded structures as expected in the first self-assembled protocells.

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Carbonyl Sulfide-Mediated Prebiotic Formation of Peptides

Cited by 388 publications

References 11 publications

The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution

The peptide-catalyzed stereospecific synthesis of tetroses: A possible model for prebiotic molecular evolution

Bioenergetics and Life's Origins

Toward Homochiral Protocells in Noncatalytic Peptide Systems

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