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Record 3 of 4571
Attempted nonenzymatic template-directed oligomerizations on a polyadenylic acid template: implications for the nature of the first genetic material
External Online Source: doi:10.1007/BF02102185
Author and Affiliation:
Stribling, R.(University of California, Department of Chemistry, San Diego, La Jolla 92093, United States)
Miller, S. L.
Abstract: Previous attempts to produce nonenzymatic template-directed oligomerizations of activated pyrimidines on polypurine templates have been unsuccessful. The only efficient reactions are those where the template is composed primarily of pyrimidines, especially cytosine. Because molecular evolution requires that a synthesized daughter polynucleotide be capable of acting as a template for the synthesis of the original polynucleotide, the one-way replication achieved thus far is inadequate to initiate an evolving system. Several uracil analogs were used in this investigation in order to search for possible replacements for uracil. The monomers used in this investigation were the imidazolides of UMP, xanthosine 5'-monophosphate, the bis-monophosphates of the acyclic nucleosides of uracil, and 2,4-quinazolinedione. The concentrations of various salts, buffers, pH, and temperature were among the different variables investigated in attempts to find conditions that would permit template-directed oligomerizations. Although the different monomers in this study demonstrated varying abilities to form very short oligomers, we were unable to detect any enhancement of this oligomerization that could be attributed to the poly(A) template. Although special conditions might be found that would allow purine-rich templates to work, these reactions cannot be considered robust. The results of our experiments suggest that pyrimidines were not part of the original replicating system on the primitive Earth. It has already been shown that ribose is an unlikely component of the first replicating systems, and we now suggest that phosphate was absent as well. This is due to the low solubility of phosphate in the present ocean (3 x 10(-6) M), as well as the difficulty of prebiotic activation of phosphates.
Publication Date: Jan 01, 1991
Document ID:
20040090119
(Acquired Sep 07, 2004)
Subject Category: EXOBIOLOGY
Document Type: Journal Article
Publication Information: Journal of molecular evolution; p. 282-8; (ISSN 0022-2844); Volume 32
Publisher Information: United States
Contract/Grant/Task Num: NAGW-20; NGT5-0296
Financial Sponsor: NASA; Washington DC United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: ABIOGENESIS; BIOLOGICAL EVOLUTION; CHEMICAL EVOLUTION; DEOXYRIBONUCLEIC ACID; GENETICS; OLIGONUCLEOTIDES; POLYNUCLEOTIDES; TEMPLATES; EXOBIOLOGY; ION CONCENTRATION; NUCLEOTIDES; PHOSPHORYLATION; PURINES; PYRIMIDINES; TEMPERATURE; URACIL
Other Descriptors: BIOGENESIS; EVOLUTION, MOLECULAR; OLIGONUCLEOTIDES/CHEMICAL SYNTHESIS; POLY A/CHEMISTRY; HYDROGEN-ION CONCENTRATION; PHOSPHORYLATION; PURINES; PYRIMIDINES; QUINAZOLINES; RIBONUCLEOTIDES; SUPPORT, U.S. GOV'T, NON-P.H.S; SUPPORT, U.S. GOV'T, P.H.S; TEMPERATURE; TEMPLATES, GENETIC; URACIL/ANALOGS & DERIVATIVES; URIDINE MONOPHOSPHATE; NASA DISCIPLINE EXOBIOLOGY; NASA DISCIPLINE NUMBER 52-20; NASA PROGRAM EXOBIOLOGY; NON-NASA CENTER
Availability Source: Other Sources
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