adenine
; cytosine
; guanine
; nucleic acid base
; rna
; uracil
; article
; biogenesis
; biosynthesis
; decomposition
; high temperature
; hydrolysis
; ph
; priority journal
; rna sequence
; NASA Discipline Exobiology
; Non-NASA Center
; Animals
; Base Composition
; Evolution, Molecular
; Humans
; RNA
; Temperature
英文摘要:
High-temperature origin-of-life theories require that the components of the first genetic material are stable. We therefore have measured the half- lives for the decomposition of the nucleobases. They have been found to be short on the geologic time scale. At 100°C, the growth temperatures of the hyperthermophiles, the half-lives are too short to allow for the adequate accumulation of these compounds (t( 1/4 ) for A and G ≃ 1 yr; U = 12 yr; C = 19 days). Therefore, unless the origin of life took place extremely rapidly (< 100 yr), we conclude that a high-temperature origin of life may be possible, but it cannot involve adenine, uracil, guanine, or cytosine. The rates of hydrolysis at 100°C also suggest that an ocean-boiling asteroid impact would reset the prebiotic clock, requiring prebiotic synthetic processes to begin again. At 0°C, A, U, G, and T appear to be sufficiently stable (t(1/2) ≤ 106 yr) to be involved in a low-temperature origin of life. However, the lack of stability of cytosine at 0°C °(t(1/2) = 17,000 yr) raises the possibility that the GC base pair may not have been used in the first genetic material unless life arose quickly (<106 yr) after a sterilization event. A two-letter code or an alternative base pair may have been used instead.
Levy, M., Dept. of Chemistry and Biochemistry, Univ. of California at San Diego, San Diego, CA 92093-0506, United States; Miller, S.L., Dept. of Chemistry and Biochemistry, Univ. of California at San Diego, San Diego, CA 92093-0506, United States
Recommended Citation:
Levy M.,Miller S.L.. The stability of the RNA bases: Implications for the origin of life[J]. Proceedings of the National Academy of Sciences of the United States of America,1998-01-01,95(14)