Chemical evolution synthesis

The term chemical evolution" was introduced by the Nobel Prize winner Melvin Calvin and refers to the process of the synthesis of biochemically important molecules from small molecules and certain chemical elements under the (hypothetical) conditions present on prebiotic Earth. It is assumed that the smaller building block molecules such as amino acids, fatty acids or nucleobases were formed initially, and that these underwent polycondensation to give macromolecules in later stages of development. 

A fundamental question for all reactions which could have been involved in the early phase of chemical evolution is that of the origin of the reduction equivalents necessary for the autotrophic synthesis. For example, the synthesis of one molecule of glucose from carbon dioxide requires 24 electrons, while the synthesis of the amino acid cysteine requires as many as 26 electrons per molecule of amino acid ... 

By studying the X-ray line of iron at 6.7 keV, we will greatly improve our understanding of the progressive synthesis of metals, and more generally, the chemical evolution of the cosmos. The composition, mass and temperature of the true intergalactic medium, which seems to be dominated by a very hot gas with filamentary structure, should also be revealed by XEUS, a marvellous balcony looking out across the Universe. May we relish the prospect ... 

The idea that the first living systems, which resulted from a process of chemical evolution beginning with the synthesis and accumulation of organic compounds (i.e., the heterotrophic hypothesis), gained significant support in 1953. This was when Stanley L. Miller, then a graduate student working with Harold C. Urey at the... 

Ferris and Antonucci73 have reported a photochemical synthesis of imidazo[4,5-d]imidazole (80) from 4-aminoimidazole-5-carbonitrile (78), which has attracted interest since 78, and its photochemical precursor diaminomaleonitrile (77) have been proposed74 as key intermediates in the prebiotic chemical evolution of purines. Mechanistic studies7311 suggest that the fused pyrazole 79 may be an intermediate. 

The origin of life probably occurred in three phases (fig. 1.23) (1) The earliest phase was a period of chemical evolution during which the compounds needed for the nu-cleation of life must have been formed. These compounds include the most important class of biological macromolecules, the nucleic acids. In this phase of evolution, the synthesis of nucleic acids was noninstructed. (2) As soon as some nucleic acids were present, physical forces between them must have led to an instructed synthesis, in which the already formed molecules served as templates for the synthesis of new polymers. It seems likely that feedback loops selected out certain nucleic acids for preferential synthesis. At some point during this period of instructed synthesis more nucleic acids and possibly protein macromolecules were formed. The products of this phase of mo-... 

However, before bacteria could evolve, the fundamental chemistry of life needed to be established. For this we need to turn back the clock to around 4.5 - 4.1 billion years ago where the earth s crust has cooled and solidified and the oceans and atmosphere begin to form. It is speculated that iron-sulfide synthesis along deep oceanic platelets may have lead to the synthesis of the first RNA and self-replicating molecules. Exactly how this chemical evolution came about remains an open question. It is possible that RNA may have used clays and similar self-replicating materials as substrates. Eventually, this... 

The dynamic process is akin to the error checking mechanisms employed in protein synthesis each reaction is reversible until the correct product has formed. In any evolutionary chemical system it is important to ensure copying fidelity and the success of dynamic combinatorial libraries indicates that concepts associate with supramolecular chemistry can be valuable in advancing chemical evolution. 

Ferris, J. P, and Hagan, W. J. (1984) HCN and Chemical Evolution The Possible Role of Cyano Compounds in Prebiotic Synthesis, Tetrahedron, 40, 1093-1120. It should be kept in mind that the compounds described in this paper do not have the foundation attached. 

L. Le Port, E. Etaix, P. Godin, P. Leduc and R. Buvet (1971). Archetypes of present day process of transphosphorylation, transacylation and peptide synthesis. In R. Buvet and C. Ponnemperuma (Eds), Molecular Evolution, Chemical Evolution and Origin of Life, Vol. 1, North-Holland, Amsterdam, The Netherlands, p. 197. 

Actually, much of the experimental work on chemical evolution (cf. Lemmon, 19701 utilizes such unstable compoumls, e.g. HCN, HCHO, HC=CCN, H2NCN, etc., on the grounds that they can be made by Miller-Urey reactions. But they can also be made by spontaneous reactions of CO, NH3, and Hj (Anders et al., 1974). Hence this class of reactions provides some common ground between the two main types of abiotic synthesis. 

Feng DF, Cho G, Doolittle RF (1997) Determining divergence times with a protein clock update and reevaluation. Proc Nat Acad Sci USA 94 13028-13033 Ferrari G, Cultrera R (1961) Photochemical synthesis of amino-acids and a new transamination process by transfer of free amino-radicals. Nature 190 326-328 Ferris JP, Chen CT (1975) Chemical evolution. XXVI. Photochemistry of methane, nitrogen and water mixtures as... 

Amend JP, Schock EL. Energetics of amino acid synthesis in hydrothermal ecosystems. Science 1998 281 1659-1662. Yanagawa H, Kobayashi K. An experimental approach to chemical evolution in submarine hydrothermal systems. Orig. Life Evol. Biosph. 1992 22 147-159. 

Ferris JP, Joshi PC, Lawless JG. Chemical evolution XXIX. Pyrimidines from hydrogen cyanide. Biosystems 1977 9 81-86. Voet AB, Schwartz AW. Uracil synthesis via HCN oligomerization. Orig. Life 1982 12 45-49. 

Ferris JP, Zamek OS, Altbuch AM, Freiman H. Chemical evolution. 18. Synthesis of pyrimidines from guanidine and cyanoac-etaldehyde. J. Mol. Evol. 1974 3 301-309. 

It is unknown when and how cooperation with amino acids, peptides, and proteins started to evolve into an RNA-protein world. However, there is an upper size limit of RNAs, which is due to a threshold error of RNA replication. The heart of the core necessary to launch the process of chemical evolution towards the RNA world must have consisted of a number of pathways for the synthesis of organic molecules from CO2, N2, and H2. Additional pathways for the synthesis of amino acids, ribose, purines, pyrimidines, coenzymes, and lipids likely combined into this core. Overall, the number of pathways required to generate nucleotides is relatively small. Pyruvate, ammonia, carbon dioxide, ATP, and glyoxalate suffice to synthesize virtually the compounds required for metabolic cycles. It seems likely that once the RNA world existed that thereafter an RNA-Peptide world developed. Details are on the following website http //www.sciencedirect.com - Cell, Volumel36, Issue 4, page 599, and a description follow below. 

Ferris JP, Hagan J (1984) HCN and chemical evolution the possible role of cyano compounds in prebiotic synthesis. Tetrahedron 40 1093-1125... 

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