Formation of specific amino acid sequences during thermal polymerization of amino acids

Hartmann, Jürgen; Brand, M. Christel; Dose, Klaus

doi:10.1016/0303-2647(81)90055-1

Cited by 77 publications

(28 citation statements)

References 14 publications

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“…Besides, at the temperature of this reaction (180 °C), we may expect that there is little stereoselective effect between R 1 and R 2 to obtain near equimolar amounts of both trimers. This conjecture has been proven to be correct with exact equimolar amounts when R 1 and R 2 are Gly and Tyr (Hartmann et al, 1981).…”

Section: The Elongation Stagementioning

confidence: 86%

“…The reaction mechanism for the synthesis of trimers containing tyrosine is known (Hartmann et al, 1981). From such work, it is clear that a main route to oligomerization is through the chemical reaction of diketopiperazine molecules with other species.…”

Section: The Elongation Stagementioning

confidence: 99%

“…(We remark that these authors studied only tyrosine containing tri-peptides). Furthermore, a mechanistic study of this reaction has been performed (Hartmann et al, 1981).…”

Section: Mathematical Models In the Prebiotic Synthesis Of Polypeptidesmentioning

confidence: 99%

“…We now allow an initiator molecule, let's say pyrGlu (Figure 4), to react with a given diketopiperazine molecule with residue groups R 1 and R 2 (Figure 6) to yield two tripeptides (both tripeptides are p − ) ( Figure 7) We envisage that a diketopiperazine molecule with residue groups R 1 and R 2 is cleaved by pyroGlu and yields the two possible linear trimers pyroGlu-R 1 -R 2 and pyroGlu-R 2 -R 1 (Hartmann et al, 1981), as in Figure 7. Notice that both trimers reconstitute a free carboxylic group at their growing end (p -), equivalent to that of pyroGlu (p -).…”

Section: The Elongation Stagementioning

confidence: 99%

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An interpretation of the oligomerization of amino acids under prebiotic conditions

P.S.

Negrón‐Mendoza

Ramos-Bernal

2015

BSGM

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In the present work we address to the oligomerization of amino acids under plausible prebiotic conditions and within the framework of a simple stochastic mathematical model. A main premise of our approach is that the reactivity of such monomers is different, as experimental results suggest. Such condition would lead to the synthesis of random but biased polymers and not to purely random polymers. Another manner to phrase such result is to say that synthesized prebiotic oligopeptides have a limited randomness. To consider oligomerization of amino acids, we follow a classification of amino acids into 4 groups: Polar positive (p + ), polar negative (p -), neutral (n), and non-polar (np). Besides, we choose to use Markov chains to evaluate the reactivity among them, as it is a process or succession of events developing in time in which the result in any stage depends on chance, according to pre-established probabilities of reaction. So, we arrange all possible pair-wise electromagnetic interactions into a 4 x 4 reactivity matrix. Then we apply this mathematical model to every stage of the diketopiperazine reaction: Its initiation and elongation stages. The chemical nature of the amino acid monomers provides only a limited number of initiators to the oligomerization process. Besides, on close examination of the elongation stage it is revealed that oligopeptides are produced only the odd-mer species, but none pair-mer peptides. Furthermore, the mathematical model predicts the existence of a Markov chain steady state which limits still more the variability in the population of synthesized oligomers. We emphasize then that the polypeptides that were produced in a prebiotic environment were random, of course, but were biased and had a restricted randomness, due to differences in the polarity of the participating amino acids. Another important observation from this study is that it can be envisaged that contiguous alike charges or monomers will not be favored in the oligomerization process under consideration, based on simple physical criteria. On the contrary, it would be easier to unite contiguous charges of different polarity. With this background, we predict that for the oligopeptides so produced, the heteropeptides would be more prevalent than the homoligopeptides. Such conditions will be useful in the prebiotic environment because presumably heteroligopeptides would have more pre-catalytic activities than homoligopeptides. We see, then, a natural emergence and predominance of complex polypeptides (co-polypeptides and hetero-polypeptides) over simpler homo-polypeptides. This is undoubtedly an interesting result.Finally, in respect to the biased principle, it is obviously insufficient drawing conclusions from scarce experimental results and from very short oligomers (i.e. tripeptides). A quantitative evaluation of the extent of bias has to be done. The extent and effectiveness of such principle will remain an open question.

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Section: The Elongation Stagementioning

confidence: 86%

Section: The Elongation Stagementioning

confidence: 99%

“…(We remark that these authors studied only tyrosine containing tri-peptides). Furthermore, a mechanistic study of this reaction has been performed (Hartmann et al, 1981).…”

Section: Mathematical Models In the Prebiotic Synthesis Of Polypeptidesmentioning

confidence: 99%

Section: The Elongation Stagementioning

confidence: 99%

See 2 more Smart Citations

An interpretation of the oligomerization of amino acids under prebiotic conditions

P.S.

Negrón‐Mendoza

Ramos-Bernal

2015

BSGM

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“…A polimerização térmica de aminoácidos em estado sólido com e sem minerais tem sido estudada por diversos autores, entretanto estes experimentos têm mostrado uma grande incorporação de aminoácidos nos peptídeos com grupo R carregados [49][50][51][52] . Este processo de síntese de peptídeos provavelmente não teve importância para a origem dos peptídeos/proteínas.…”

Section: Experimentos Envolvendo Mineraisunclassified

Adsorção de aminoácidos sobre minerais e a origem da vida

Zaia¹,

Zaia²

2006

Quím. Nova

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Recebido em 30/3/05; aceito em 15/7/05; publicado na web em 6/3/06 ADSORPTION OF AMINO ACIDS ON MINERALS AND THE ORIGIN OF LIFE. Minerals adsorb more readily amino acids with charged R groups than those with uncharged R groups, so that the incorporation of amino acids with charged R groups into peptides would be more frequent than that of amino acids with uncharged R groups. However, 74% of the amino acids in the proteins of modern organisms contain uncharged R groups. Thus, what could have been the mechanism that produced peptides/ proteins with more amino acids with uncharged R groups than precursors with charged R groups? The lipid world offers an alternative view of the origin of life. In the present paper, several other mechanisms are also discussed.Keywords: adsorption; minerals; amino acids. INTRODUÇÃOPodemos dizer que a grande maioria das reações químicas, que ocorrem em todos os seres vivos do nosso planeta, de alguma forma envolve proteínas e peptídeos e, em alguns casos, aminoácidos 1 . Por este motivo, a questão da formação de aminoácidos na Terra primitiva e sua condensação para peptídeos é um assunto extremamente importante para a química prebiótica. Neste artigo vamos partir do pressuposto que aminoácidos existiam em uma quantidade razoável na Terra primitiva. Podemos considerar, com uma boa margem de segurança, que esta suposição esteja correta visto que aminoácidos são facilmente sintetizados em diversos ambientes da química prebiótica, tais como mistura gasosas tanto de atmosferas redutoras como oxidantes 2-5 ; reações em estado sólido 6 ; reações simulando fontes hidrotermais ou em meio aquoso [7][8][9][10][11] . Também devemos lembrar que cometas e meteoros podem ter contribuído com uma parcela dos aminoácidos existentes na Terra primitiva 12,13 . Logo após o celebre experimento de Miller 2 , diversos pesquisadores colocaram a seguinte questão: os aminoácidos formados na atmosfera, que não fossem destruídos pela forte radiação ultravioleta do nosso jovem Sol, cairiam no mar da Terra primitiva e sendo este mar muito grande (como é nos dias de hoje) os aminoácidos seriam muito diluídos impossibilitando a formação de peptídeos ou proteínas e, desta forma, impedindo a evolução molecular. O mesmo problema ocorreria para o caso dos aminoácidos produzidos em fontes hidrotermais ou no mar ou trazidos por cometas ou meteoros que caíssem no mar. Para resolver o problema da grande diluição dos aminoácidos, Bernal 14 sugeriu que os minerais tivessem um papel importante na pré-concentração dos aminoácidos, devido a suas propriedades de bons adsorventes, e agissem também como catalisadores na formação dos peptídeos e proteínas. Portanto, os minerais poderiam ter selecionado os aminoácidos e catalisado sua reação para formação de peptídeos e proteínas. Neste artigo vamos tratar da questão da participação dos minerais na pré-concentração dos aminoácidos. ADSORÇÃO DE BIOMOLÉCULAS SOBRE MINERAISDevemos salientar que os minerais obviamente tiveram provavelmente também uma participação importante na adsorção de ...

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Präbiotische Evolution und der Ursprung des Lebens

Dose¹

1987

Chemie in nserer Zeit

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Innerhalb der Naturwissenschaften wird heute allgemein angenommen, daß das Leben über eine Folge von Evolutionsschritten durch Selbstorganisation von Molekülen oder Molekülkomplexen entstanden ist. Von diesen mokekularen Bausteinen wird wiederum ‐ zumindest für die Erde ‐ vermutet, daß sie vor allem durch Einwirkung verschiedener Energieformen auf die Bestandteile der frühen Atmosphäre und Hydrosphäre gebildet wurden. Zur Zeit werden Folgende Evolutionsstadien diskutiert: Die Selbstorganisation von solchen spontan gebildeten präbiotischen Molekülen zu den ersten Zellen (Protobionten oder Protozellen), deren („protodarwinsche”︁) Evolution zu Progenoten und die Darwinsche Evolution von Progenoten zu den drei Reichen heutiger Organismen: Archaebakterien, Eubakterien, Eukaryoten (Abbildung 1). Beträchtliche Meinungsverschiedenheiten bestehen jedoch unter den Wissenschaftlern über Details der einzelnen Evolutionsschritte. Das Problem ist, daß alle bisher diskutierten Evolutionsschritte von präbiotischen Molekülen zu den Progenoten weitgehend hypothetisch sind. Dasselbe gilt für die Vorstellungen über die Umgebungsbedingungen, die während der einzelen Evolutionsschritte auf der frühen Erde herrschten. Viele Schwierigkeiten bestehen darüber hinaus im Hinblick auf die Laborsimulation der Präbiotischen Bildung der meisten molekularen Bausteine, dies gilt vor allem für die Bildung von replikationsfähigen Polynucleotiden, einfachen Nucleotiden, von Ribose und Desoxyribose sowie auch für die Anhäufung optisch reiner D‐ oder L‐Formen. Das Gebiet befindet sich zur Zeit in einem Zustand der Stagnation. Um aus diesem Zustand herauszukommen, werden grundsätzlich neue Anstöß benötigt. Derartige Anstöße könnten u.a. aus den Bereichen der Molekularbiologie sowie der Planetenforschung und der Kosmochemie kommen. Bessere Vorstellungen über die Umgebungsbedingungen auf der primitiven Erde könnte beispielsweise eine Erforschung der Marsoberfläche liefern. Es wird nämlich angenommen, daß sich weite Teile der Marsoberfläche noch heute in einem Zustand befinden, in dem sich die Erde vor etwa vier Milliarden Jahren befand. Entsprechende Daten werden voraussichtlich innerhalb der nächsten 15 Jahre zur Verfügung stehen.

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Formation of specific amino acid sequences during thermal polymerization of amino acids

Cited by 77 publications

References 14 publications

An interpretation of the oligomerization of amino acids under prebiotic conditions

An interpretation of the oligomerization of amino acids under prebiotic conditions

Adsorção de aminoácidos sobre minerais e a origem da vida

Präbiotische Evolution und der Ursprung des Lebens

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