- Prebiotic selection and assembly of proteinogenic amino acids and natural nucleotides from complex mixtures
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A central problem for the prebiotic synthesis of biological amino acids and nucleotides is to avoid the concomitant synthesis of undesired or irrelevant by-products. Additionally, multistep pathways require mechanisms that enable the sequential addition of reactants and purification of intermediates that are consistent with reasonable geochemical scenarios. Here, we show that 2-aminothiazole reacts selectively with two- and three-carbon sugars (glycolaldehyde and glyceraldehyde, respectively), which results in their accumulation and purification as stable crystalline aminals. This permits ribonucleotide synthesis, even from complex sugar mixtures. Remarkably, aminal formation also overcomes the thermodynamically favoured isomerization of glyceraldehyde into dihydroxyacetone because only the aminal of glyceraldehyde separates from the equilibrating mixture. Finally, we show that aminal formation provides a novel pathway to amino acids that avoids the synthesis of the non-proteinogenic α,α-disubstituted analogues. The common physicochemical mechanism that controls the proteinogenic amino acid and ribonucleotide assembly from prebiotic mixtures suggests that these essential classes of metabolite had a unified chemical origin.
- Islam, Saidul,Bu?ar, Dejan-Kre?imir,Powner, Matthew W.
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p. 584 - 589
(2017/05/31)
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- Common origins of RNA, protein and lipid precursors in a cyanosulfidic protometabolism
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A minimal cell can be thought of as comprising informational, compartment-forming and metabolic subsystems. To imagine the abiotic assembly of such an overall system, however, places great demands on hypothetical prebiotic chemistry. The perceived differences and incompatibilities between these subsystems have led to the widely held assumption that one or other subsystem must have preceded the others. Here we experimentally investigate the validity of this assumption by examining the assembly of various biomolecular building blocks from prebiotically plausible intermediates and one-carbon feedstock molecules. We show that precursors of ribonucleotides, amino acids and lipids can all be derived by the reductive homologation of hydrogen cyanide and some of its derivatives, and thus that all the cellular subsystems could have arisen simultaneously through common chemistry. The key reaction steps are driven by ultraviolet light, use hydrogen sulfide as the reductant and can be accelerated by Cu(I)-Cu(II) photoredox cycling.
- Patel, Bhavesh H.,Percivalle, Claudia,Ritson, Dougal J.,Duffy, Colm D.,Sutherland, John D.
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p. 301 - 307
(2015/04/14)
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- Process for the preparation of enantiomerically enriched compounds
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1. Process for the preparation of enantiomerically enriched amino aldehydes and amino alcohols, wherein a corresponding enantiomerically enriched amino nitrile is subjected to hydrogenation in the presence of hydrogen, a hydrogenation catalyst, preferably a Pd-catalyst and a mineral acid. For the preparation of an amino aldehyde hydrogen preferably is present at a hydrogen-pressure between 0.1 and 2 MPa, in particular between 0.5 and 1 MPa. The amino aldehyde preferably is isolated in the form of a chemically and configurationally stable derivative. For the preparation of an amino alcohol, preferably at least during part of the hydrogenation hydrogen is present at a hydrogen-pressure between 2 and 10 MPa, in particular between 4 and 6 MPa. In a preferred embodiment the hydrogen-pressure initially is between 0,5 and 2 MPa and subsequently, after most of the nitrile starting material is converted, the hydrogen pressure is increased to a value between 2 and 10 MPa. The enantiomerically enriched nitrile starting material may a.o. be prepared by enzymatic resolution, classical resolution, resolution via preferential crystallization, diastereomeric synthesis, catalytic asymmetric synthesis or dehydratation of amino acid amides.
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Page/Page column 4-5
(2010/11/29)
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- Chemie der α-Aminonitrile. 1. Mitteilung. Einleitung und Wege zu Uroporphyrinogen-octanitrilen
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Chemistry of α-Aminonitriles I: Introduction and Pathways to Uroporphyrinogen-octanitriles.An introduction to experimental studies on the chemistry of α-aminonitriles potentially relevant to the problems of prebiotic chemistry is presented.The framework of conditions wherein the investigations is chosen to be carried out implies both molecular oxygen and - whenever feasible - water to be excluded from reaction conditions.This study focusses on 2-amino-2-propenenitrile (3) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5).Schemes 13, 16, 23 as well as 25, and 26 summarize reaction sequences by which 3 is tranformed within the definied framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroporphyrinogen-octanitriles 57-60.HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one present in all biological porphinoids.Preparative procedures for the synthesis of 3 (Scheme 9), the β,β-disubstututed pyrrol-nitriles 30, 53, and 54 (Scheme 19) as well as the porphyrinogen-octakis(propionitrile) and -octakis(acetonitrile) 65 and 66, respectively (Scheme 24) are given.
- Ksander, Gary,Bold, Guido,Lattmann, Rene,Lehmann, Christian,Frueh, Thomas,et al.
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p. 1115 - 1172
(2007/10/02)
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- Useful Synthesis of α-Aminonitriles by Means of Alumina and Ultrasound
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Combined use of alumina and ultrasound facilitates the synthesis of α-aminonitriles under solid-liquid two phase conditions from carbonyl compounds, salts of amines and potassium cyanide in organic solvents.
- Hanafusa, Terukiyo,Ichihara, Junko,Ashida, Tetsuya
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p. 687 - 690
(2007/10/02)
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