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Prebiotic chemistry

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https://www.readbyqxmd.com/read/28397774/small-and-random-peptides-an-unexplored-reservoir-of-potentially-functional-primitive-organocatalysts-the-case-of-seryl-histidine
#1
REVIEW
Rafal Wieczorek, Katarzyna Adamala, Tecla Gasperi, Fabio Polticelli, Pasquale Stano
Catalysis is an essential feature of living systems biochemistry, and probably, it played a key role in primordial times, helping to produce more complex molecules from simple ones. However, enzymes, the biocatalysts par excellence, were not available in such an ancient context, and so, instead, small molecule catalysis (organocatalysis) may have occurred. The best candidates for the role of primitive organocatalysts are amino acids and short random peptides, which are believed to have been available in an early period on Earth...
April 9, 2017: Life
https://www.readbyqxmd.com/read/28383486/prebiotic-factors-influencing-the-activity-of-a-ligase-ribozyme
#2
Fabrizio Anella, Christophe Danelon
An RNA-lipid origin of life scenario provides a plausible route for compartmentalized replication of an informational polymer and subsequent division of the container. However, a full narrative to form such RNA protocells implies that catalytic RNA molecules, called ribozymes, can operate in the presence of self-assembled vesicles composed of prebiotically relevant constituents, such as fatty acids. Hereby, we subjected a newly engineered truncated variant of the L1 ligase ribozyme, named tL1, to various environmental conditions that may have prevailed on the early Earth with the objective to find a set of control parameters enabling both tL1-catalyzed ligation and formation of stable myristoleic acid (MA) vesicles...
April 6, 2017: Life
https://www.readbyqxmd.com/read/28378591/semiconductor-photocatalysis-for-chemoselective-radical-coupling-reactions
#3
Horst Kisch
Photocatalysis at semiconductor surfaces is a growing field of general photocatalysis because of its importance for the chemical utilization of solar energy. By analogy with photoelectrochemistry the basic mechanism of semiconductor photocatalysis can be broken down into three steps: photogenerated formation of surface redox centers (electron-hole pairs), interfacial electron transfer from and to substrates (often coupled with proton-transfer), and conversion of primary redox intermediates into the products...
April 5, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28338703/theoretical-investigation-of-proton-collisions-on-prebiotic-candidates-hydrogen-cyanide-polymers
#4
Marie-Christine Bacchus-Montabonel
One of the major concerns in prebiotic chemistry is the formation and destruction routes of prebiotic compounds in space. As detected for a long time, hydrogen cyanide (HCN) has been suggested to be a feedstock molecule at the origin of life driving easy oligomerization, in particular to form adenine. This may focus on its first oligomers because its dimer cyanomethanimine was recently observed in star-forming regions, or its trimer aminomalononitrile. With regard to the assumption of an extra-terrestrial origin of life, the stability of such species under ultraviolet radiation or in ion-collisions is an open question...
March 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28338689/a-prebiotically-plausible-synthesis-of-pyrimidine-%C3%AE-ribonucleosides-and-their-phosphate-derivatives-involving-photoanomerization
#5
Jianfeng Xu, Maria Tsanakopoulou, Christopher J Magnani, Rafał Szabla, Judit E Šponer, Jiří Šponer, Robert W Góra, John D Sutherland
Previous research has identified ribose aminooxazoline as a potential intermediate in the prebiotic synthesis of the pyrimidine nucleotides with remarkable properties. It crystallizes spontaneously from reaction mixtures, with an enhanced enantiomeric excess if initially enantioenriched, which suggests that reservoirs of this compound might have accumulated on the early Earth in an optically pure form. Ribose aminooxazoline can be converted efficiently into α-ribocytidine by way of 2,2'-anhydroribocytidine, although anomerization to β-ribocytidine by ultraviolet irradiation is extremely inefficient...
April 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28323482/constraints-on-the-early-terrestrial-surface-uv-environment-relevant-to-prebiotic-chemistry
#6
Sukrit Ranjan, Dimitar D Sasselov
The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28298101/acetonitrile-cluster-solvation-in-a-cryogenic-ethane-methane-propane-liquid-implications-for-titan-lake-chemistry
#7
L René Corrales, Thomas D Yi, Samantha K Trumbo, David Shalloway, Jonathan I Lunine, David A Usher
The atmosphere of Titan, Saturn's largest moon, exhibits interesting UV- and radiation-driven chemistry between nitrogen and methane, resulting in dipolar, nitrile-containing molecules. The assembly and subsequent solvation of such molecules in the alkane lakes and seas found on the moon's surface are of particular interest for investigating the possibility of prebiotic chemistry in Titan's hydrophobic seas. Here we characterize the solvation of acetonitrile, a product of Titan's atmospheric radiation chemistry tentatively detected on Titan's surface [H...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28277783/origin-of-life-and-the-phosphate-transfer-catalyst
#8
Radosław W Piast, Rafał M Wieczorek
In this paper, we revisit several issues relevant to origin-of-life research and propose a Phosphate Transfer Catalyst hypothesis that furthers our understanding of some of the key events in prebiotic chemical evolution. In the Phosphate Transfer Catalyst hypothesis, we assume the existence of hypothetical metallopeptides with phosphate transfer activity that use abundant polyphosphates as both substrates and energy sources. Nonspecific catalysis by this phosphate transfer catalyst would provide a variety of different products such as phosphoryl amino acids, nucleosides, polyphosphate nucleotides, nucleic acids, and aminoacylated nucleic acids...
March 2017: Astrobiology
https://www.readbyqxmd.com/read/28231175/mushroom-polysaccharides-chemistry-and-antiobesity-antidiabetes-anticancer-and-antibiotic-properties-in-cells-rodents-and-humans
#9
REVIEW
Mendel Friedman
More than 2000 species of edible and/or medicinal mushrooms have been identified to date, many of which are widely consumed, stimulating much research on their health-promoting properties. These properties are associated with bioactive compounds produced by the mushrooms, including polysaccharides. Although β-glucans (homopolysaccharides) are believed to be the major bioactive polysaccharides of mushrooms, other types of mushroom polysaccharides (heteropolysaccharides) also possess biological properties. Here we survey the chemistry of such health-promoting polysaccharides and their reported antiobesity and antidiabetic properties as well as selected anticarcinogenic, antimicrobial, and antiviral effects that demonstrate their multiple health-promoting potential...
November 29, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28209893/localized-aliphatic-organic-material-on-the-surface-of-ceres
#10
M C De Sanctis, E Ammannito, H Y McSween, A Raponi, S Marchi, F Capaccioni, M T Capria, F G Carrozzo, M Ciarniello, S Fonte, M Formisano, A Frigeri, M Giardino, A Longobardo, G Magni, L A McFadden, E Palomba, C M Pieters, F Tosi, F Zambon, C A Raymond, C T Russell
Organic compounds occur in some chondritic meteorites, and their signatures on solar system bodies have been sought for decades. Spectral signatures of organics have not been unambiguously identified on the surfaces of asteroids, whereas they have been detected on cometary nuclei. Data returned by the Visible and InfraRed Mapping Spectrometer on board the Dawn spacecraft show a clear detection of an organic absorption feature at 3.4 micrometers on dwarf planet Ceres. This signature is characteristic of aliphatic organic matter and is mainly localized on a broad region of ~1000 square kilometers close to the ~50-kilometer Ernutet crater...
February 17, 2017: Science
https://www.readbyqxmd.com/read/28119504/synchronized-chaotic-targeting-and-acceleration-of-surface-chemistry-in-prebiotic-hydrothermal-microenvironments
#11
Aashish Priye, Yuncheng Yu, Yassin A Hassan, Victor M Ugaz
Porous mineral formations near subsea alkaline hydrothermal vents embed microenvironments that make them potential hot spots for prebiotic biochemistry. But, synthesis of long-chain macromolecules needed to support higher-order functions in living systems (e.g., polypeptides, proteins, and nucleic acids) cannot occur without enrichment of chemical precursors before initiating polymerization, and identifying a suitable mechanism has become a key unanswered question in the origin of life. Here, we apply simulations and in situ experiments to show how 3D chaotic thermal convection-flows that naturally permeate hydrothermal pore networks-supplies a robust mechanism for focused accumulation at discrete targeted surface sites...
February 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28067845/selection-of-prebiotic-molecules-in-amphiphilic-environments
#12
Christian Mayer, Ulrich Schreiber, María J Dávila
A basic problem in all postulated pathways of prebiotic chemistry is the low concentration which generally is expected for interesting reactants in fluid environments. Even though compounds, like nucleobases, sugars or peptides, principally may form spontaneously under environmental conditions, they will always be rapidly diluted in an aqueous environment. In addition, any such reaction leads to side products which often exceed the desired compound and generally hamper the first steps of a subsequent molecular evolution...
January 7, 2017: Life
https://www.readbyqxmd.com/read/28001448/following-the-interstellar-history-of-carbon-from-the-interiors-of-stars-to-the-surfaces-of-planets
#13
L M Ziurys, D T Halfen, W Geppert, Y Aikawa
The chemical history of carbon is traced from its origin in stellar nucleosynthesis to its delivery to planet surfaces. The molecular carriers of this element are examined at each stage in the cycling of interstellar organic material and their eventual incorporation into solar system bodies. The connection between the various interstellar carbon reservoirs is also examined. Carbon has two stellar sources: supernova explosions and mass loss from evolved stars. In the latter case, the carbon is dredged up from the interior and then ejected into a circumstellar envelope, where a rich and unusual C-based chemistry occurs...
December 2016: Astrobiology
https://www.readbyqxmd.com/read/27995274/emergence-of-life-on-earth-a-physicochemical-jigsaw-puzzle
#14
REVIEW
Jan Spitzer
We review physicochemical factors and processes that describe how cellular life can emerge from prebiotic chemical matter; they are: (1) prebiotic Earth is a multicomponent and multiphase reservoir of chemical compounds, to which (2) Earth-Moon rotations deliver two kinds of regular cycling energies: diurnal electromagnetic radiation and seawater tides. (3) Emerging colloidal phases cyclically nucleate and agglomerate in seawater and consolidate as geochemical sediments in tidal zones, creating a matrix of microspaces...
January 2017: Journal of Molecular Evolution
https://www.readbyqxmd.com/read/27924306/the-future-of-prebiotic-chemistry
#15
Alexander J Wagner, Donna G Blackmond
No abstract text is available yet for this article.
November 23, 2016: ACS Central Science
https://www.readbyqxmd.com/read/27909555/effect-of-dual-type-oligosaccharides-on-constipation-in-loperamide-treated-rats
#16
Sung Hee Han, Ki Bae Hong, Eun Young Kim, So Hyun Ahn, Hyung Joo Suh
BACKGROUND/OBJECTIVES: Constipation is a condition that can result from intestinal deformation. Because humans have an upright posture, the effects of gravity can cause this shape deformation. Oligosaccharides are common prebiotics and their effects on bowel health are well known. However, studies of the physiological functionality of a product that contains both lactulose and galactooligosaccharides are insufficient. We investigated the constipation reduction effect of a dual-type oligosaccharide, Dual-Oligo, in loperamide-treated rats...
December 2016: Nutrition Research and Practice
https://www.readbyqxmd.com/read/27862722/evaporite-borate-containing-mineral-ensembles-make-phosphate-available-and-regiospecifically-phosphorylate-ribonucleosides-borate-as-a-multifaceted-problem-solver-in-prebiotic-chemistry
#17
Hyo-Joong Kim, Yoshihiro Furukawa, Takeshi Kakegawa, Andrei Bita, Romulus Scorei, Steven A Benner
RNA is currently thought to have been the first biopolymer to support Darwinian natural selection on Earth. However, the phosphate esters in RNA and its precursors, and the many sites at which phosphorylation might occur in ribonucleosides under conditions that make it possible, challenge prebiotic chemists. Moreover, free inorganic phosphate may have been scarce on early Earth owing to its sequestration by calcium in the unreactive mineral hydroxyapatite. Herein, it is shown that these problems can be mitigated by a particular geological environment that contains borate, magnesium, sulfate, calcium, and phosphate in evaporite deposits...
December 19, 2016: Angewandte Chemie
https://www.readbyqxmd.com/read/27827919/taming-prebiotic-chemistry-the-role-of-heterogeneous-and-interfacial-catalysis-in-the-emergence-of-a-prebiotic-catalytic-information-polymer-system
#18
REVIEW
Pierre-Alain Monnard
Cellular life is based on interacting polymer networks that serve as catalysts, genetic information and structural molecules. The complexity of the DNA, RNA and protein biochemistry suggests that it must have been preceded by simpler systems. The RNA world hypothesis proposes RNA as the prime candidate for such a primal system. Even though this proposition has gained currency, its investigations have highlighted several challenges with respect to bulk aqueous media: (1) the synthesis of RNA monomers is difficult; (2) efficient pathways for monomer polymerization into functional RNAs and their subsequent, sequence-specific replication remain elusive; and (3) the evolution of the RNA function towards cellular metabolism in isolation is questionable in view of the chemical mixtures expected on the early Earth...
November 4, 2016: Life
https://www.readbyqxmd.com/read/27802310/non-enzymatic-oligomerization-of-3-5-cyclic-amp
#19
Giovanna Costanzo, Samanta Pino, Anna Maria Timperio, Judit E Šponer, Jiří Šponer, Olga Nováková, Ondrej Šedo, Zbyněk Zdráhal, Ernesto Di Mauro
Recent studies illustrate that short oligonucleotide sequences can be easily produced from nucleotide precursors in a template-free non-enzymatic way under dehydrating conditions, i.e. using essentially dry materials. Here we report that 3',5' cyclic AMP may also serve as a substrate of the reaction, which proceeds under moderate conditions yet with a lower efficiency than the previously reported oligomerization of 3',5' cyclic GMP. Optimally the oligomerization requires (i) a temperature of 80°C, (ii) a neutral to alkaline environment and (iii) a time on the order of weeks...
2016: PloS One
https://www.readbyqxmd.com/read/27730379/influence-of-microhydration-on-the-structures-and-proton-induced-charge-transfer-in-rna-intermediates
#20
M C Bacchus-Montabonel, F Calvo
Solvation effects are of major interest in the context of radiation damage, due to their potential applications in cancer therapy. Reliable modeling of the solvent is, however, quite challenging, and numerous studies have been devoted to isolated biomolecules and stepwise-hydrated molecules in which the amount of solvent is controlled one molecule at a time. The influence of stepwise hydration on radiation damage is investigated here using the example of proton-induced charge transfer in two biomolecular targets...
November 2016: Journal of Molecular Modeling
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