Hydroxy and α-amino acids under possible Hadean, volcanic origin-of-life conditions. Science
Section of Organic Chemistry and Biochemistry, Technische Universität München, München, Bavaria, Germany Science
(Impact Factor: 33.61).
11/2006; 314(5799):630-2. DOI: 10.1126/science.1130895
To test the theory of a chemoautotrophic origin of life in a volcanic, hydrothermal setting, we explored mechanisms for the buildup of bio-organic compounds by carbon fixation on catalytic transition metal precipitates. We report the carbon monoxide-dependent formation of carbon-fixation products, including an ordered series of alpha-hydroxy and alpha-amino acids of the general formula R-CHA-COOH (where R is H, CH3,C2H5,orHOCH2 and A is OH or NH2) by carbon fixation at 80 degrees to 120 degrees C, catalyzed by nickel or nickel,iron precipitates with carbonyl, cyano, and methylthio ligands as carbon sources, with or without sulfido ligands. Calcium or magnesium hydroxide was added as a pH buffer. The results narrow the gap between biochemistry and volcanic geochemistry and open a new gateway for the exploration of a volcanic, hydrothermal origin of life.
Available from: Stéphane La Barre
- "Contenders of the "primitive soup" scenario advocate that life may have arisen through chemoautotrophic processes occurring in oceanic depths in the vicinity of hydrothermal settings which would provide all necessary starting conditions . In this "pioneer metabo‐ lism" scenario, the generation of homochiral metalloenzymes of extant organisms from inorganic transition metal precipitates (by chelation of alpha-hydroxyl and alpha-amino acids ligands) follows a stepwise evolution by autocatalytic feedback. "
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ABSTRACT: Chemodiversity usually refers to small molecules that have a signaling (offensive or defensive) function, sometimes protective. This leaves aside larger molecules that are purely structural and those that participate in essential metabolic functions, and make up the bulk of the organic body mass of living organisms.
From cyanobacteria and bacteria to the largest metazoans, chemistry is the preferred mode of aquatic communication, thanks to the extraordinary solvation properties of water. Bacteria create biofilms inside which they communicate using their own chemical repertoire before colonizing new media, substrates or organisms. Microalgae form blooms which are maintained by releasing semiochemicals for cell-cell recognition. Fish rely on their extraordinary sense of smell to hunt or to migrate to some specific breeding spot. The extraordinary biodiversity of coral reefs is maintained by a highly complex chemical network of toxins and pheromones, some soluble, some dispersed with a mucus carrier or surface-coated. But not only: the amazing colors used for warning or for camouflage, the bioluminescence used in the dark correspond to very sophisticated assemblages of pigments, small metabolites or proteins, each organism having its own strategy to be visually recognized or to blend into the background.
Humans have only recently been aware of the extraordinary potential marine molecules for the design of new drugs, cosmetics and nutraceutics. Well over 20000 natural molecules have been studied so far, and several have responded to the need for novel anticancer, antibiotic, anti-inflammatory or anti-pain agents etc. The necessity to preserve this exceptional resource, however, has only manifested itself in the delineation of protected areas and in the implementation of codes of good practices regarding non-destructive boating and durable sampling protocols.
Over the last three decades, warning messages have been sent to the community about the destructive consequences worldwide economic development will have on biodiversity, both terrestrial and marine, during the 21st century. Direct impacts are caused by overexploitation and mismanagement of natural resources and improper recycling and disposal of waste products. Indirect impacts are caused by the accelerating volatilization of greenhouse molecules and their accumulation in the atmosphere where they may undergo undesirable speciation. Restitution of sulfur emissions to land may cause acidic rains and transfer of carbon-containing emissions to seawater increases its acidity, both leading to biodiversity destructive scenarios. Not to mention the release of man-made (synthetic) molecules, some of which like CFCs destroy the anti-UV ozone shield, others like PCBs accumulating along food chains and eventually killing top consumers. Synthetic molecules may respond to specific needs and criteria, but they will never replace natural molecules, in the same way as genetically transformed organisms will never replace wildlife diversity. Moreover, freak biological or chemical species should be eliminated safely once the purpose for which they were created has been fulfilled.
To-date, very little is said or written on the fate of natural chemodiversity within the context of local or general biodiversity collapse, both terrestrial and marine. After a brief historical account of the intricate connections between chemodiversity and biodiversity since life appeared on our planet, this chapter attempts to demonstrate that natural molecular diversity is a treasure to preserve for future generations, using a series of marine examples.
Available from: Ivo Juranek
- "Life emerged about 3.5–4 billion years ago from amino acids and nucleotides, which were synthesized utilizing free radicalmediated reactions from simple reduced inorganic compounds (Line, 2002). Necessary energy was provided by cosmic and sun radiation and geo-volcanic processes (Cody et al., 2000; Huber and Wächtershäuser, 2006). "
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ABSTRACT: Findings about involvement of reactive oxygen species (ROS) not only in defense processes, but also in a number of pathologies, stimulated discussion about their role in etiopathogenesis of various diseases. Yet questions regarding the role of ROS in tissue injury, whether ROS may serve as a common cause of different disorders or whether their uncontrolled production is just a manifestation of the processes involved, remain unexplained. Dogmatically, increased ROS formation is considered to be responsible for development of the so-called free-radical diseases. The present review discusses importance of ROS in various biological processes, including origin of life, evolution, genome plasticity, maintaining homeostasis and organism protection. This may be a reason why no significant benefit was found when exogenous antioxidants were used to treat free-radical diseases, even though their causality was primarily attributed to ROS. Here, we postulate that ROS unlikely play a causal role in tissue damage, but may readily be involved in signaling processes and as such in mediating tissue healing rather than injuring. This concept is thus in a contradiction to traditional understanding of ROS as deleterious agents. Nonetheless, under conditions of failing autoregulation, ROS may attack integral cellular components, cause cell death and deteriorate the evolving injury.
Available from: Takeshi Kakegawa
- "The abiotic polymerization of amino acids may have been essential for the formation of primordial oligopeptides on early Earth (Oparin 1957). Many researchers have suggested that various amino acids could have formed on early Earth (Huber and Wächtershäuser 2006; Furukawa et al. 2009; Goldman et al. 2010) or could have been delivered to early Earth (Cronin and Moore 1971; Hennet et al. 1992; Marshall 1994; Bernstein et al. 2002; Pizzarello et al. 2003). The oligomerization of amino acids has been investigated in many studies that aimed to simulate environments, such as submarine hydrothermal systems and tidal flats, considered to be suitable for the origin of life (Lahav et al. 1978; Huber and Wächtershäuser 1998; Bujdák and Rode 1999; Imai et al. 1999; Kawamura et al. 2005; Cleaves et al. 2009). "
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ABSTRACT: We investigated the oligomerization of solid valine and the stabilities of valine and valine peptides under conditions of high temperature (150-200 °C) and high pressure (50-150 MPa). Experiments were performed under non-aqueous condition in order to promote dehydration reaction. After prolonged exposure of monomeric valine to elevated temperatures and pressures, the products were analyzed by liquid chromatography mass spectrometry comparing their retention times and masses. We identified linear peptides that ranged in size from dimer to hexamer, as well as a cyclic dimer. Previous studies that attempted abiotic oligomerization of valine in the absence of a catalyst have never reported valine peptides larger than a dimer. Increased reaction temperature increased the dissociative decomposition of valine and valine peptides to products such as glycine, β-alanine, ammonia, and amines by processes such as deamination, decarboxylation, and cracking. The amount of residual valine and peptide yields was greater at higher pressures at a given temperature, pressure, and reaction time. This suggests that dissociative decomposition of valine and valine peptides is reduced by pressure. Our findings are relevant to the investigation of diagenetic processes in prebiotic marine sediments where similar pressures occur under water-poor conditions. These findings also suggest that amino acids, such as valine, could have been polymerized to peptides in deep prebiotic marine sediments within a few hundred million years.
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