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Prebiotic chemistry

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
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
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
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)
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
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
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
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
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
Alexander J Wagner, Donna G Blackmond
No abstract text is available yet for this article.
November 23, 2016: ACS Central Science
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
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
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
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
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
M Sanchez-Arenillas, E Mateo-Marti
We have demonstrated that the annealing process for cleaning pyrite surfaces is a critical parameter in promoting ordering on the surface and driving surface reactivity. Furthermore, we describe a spectroscopic surface characterization of the presence or absence of the surface ordering, as indicated by the Low Energy Electron Diffraction (LEED) pattern, as a function of the surface annealing process. Complementary X-ray photoemission spectroscopy (XPS) results provide evidence that longer annealing processes of over 3 hours repair the sulfur vacancies in the pyrite, making FeS species partially disappear in favor of FeS2 species...
October 5, 2016: Physical Chemistry Chemical Physics: PCCP
J Manik Nava-Sedeño, Adrian Ortiz-Cervantes, Antígona Segura, Shawn D Domagal-Goldman
Lifeless planets with CO2 atmospheres produce CO by CO2 photolysis. On planets around M dwarfs, CO is a long-lived atmospheric compound, as long as UV emission due to the star's chromospheric activity lasts, and the sink of CO and O2 in seawater is small compared to its atmospheric production. Atmospheres containing reduced compounds, like CO, may undergo further energetic and chemical processing to give rise to organic compounds of potential importance for the origin of life. We calculated the yield of organic compounds from CO2-rich atmospheres of planets orbiting M dwarf stars, which were previously simulated by Domagal-Goldman et al...
October 4, 2016: Astrobiology
Michele Fiore, Peter Strazewski
There may be more than one way leading to RNA: Recent discoveries in the synthesis of nucleoside and nucleotide precursors are described and put into the wider context of prebiotic systems chemistry. Mixing Butlerow's carbohydrate precursors with Traube's 5-formylaminopyrimidines has led to the formation of prebiotic purine nucleosides whereas the mixing of 5-phosphoribose with barbituric acid and melamine gave supramolecular fibers from stacks of Whitesides' rosettas.
September 15, 2016: Angewandte Chemie
Mariame Akouche, Maguy Jaber, Emilie-Laure Zins, Marie-Christine Maurel, Jean-Francois Lambert, Thomas Georgelin
Understanding ribose reactivity is a crucial step in the "RNA world" scenario because this molecule is a component of all extant nucleotides that make up RNA. In solution, ribose is unstable and susceptible to thermal destruction. We examined how ribose behaves upon thermal activation when adsorbed on silica, either alone or with the coadsorption of inorganic salts (MgCl2 , CaCl2 , SrCl2 , CuCl2 , FeCl2 , FeCl3 , ZnCl2 ). A combination of (13) C NMR, in situ IR, and TGA analyses revealed a variety of phenomena...
September 14, 2016: Chemistry: a European Journal
Ziwei Liu, Lukas Rigger, Jean-Christophe Rossi, John D Sutherland, Robert Pascal
5(4H)-Oxazolones can be formed through the activation of acylated α-amino acids or of peptide C termini. They constitute potentially activated intermediates in the abiotic chemistry of peptides that preceded the origin of life or early stages of biology and are capable of yielding mixed carboxylic-phosphoric anhydrides upon reaction with phosphate esters and nucleotides. Here, we present the results of a study aimed at investigating the chemistry that can be built through this interaction. As a matter of fact, the formation of mixed anhydrides with mononucleotides and nucleic acid models is shown to take place at positions involving a mono-substituted phosphate group at the 3'- or 5'-terminus but not at the internal phosphodiester linkages...
October 10, 2016: Chemistry: a European Journal
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