Origin of Life

Theories and evidence for chemical biopoieses

Ligation activity of fragmented ribozymes in frozen solution: implications for the RNA world -- Vlassov et al. 32 (9): 2966 -- Nucleic Acids Research

Ligation activity of fragmented ribozymes in frozen solution: implications for the RNA world -- Vlassov et al. 32 (9): 2966 -- Nucleic Acids Research: "The RNA World (1-3) refers to an evolutionary period prior to coded peptide synthesis in which RNA may have been the major genetic and catalytic agent. If the prebiotic conditions were 'warm and wet' as is usually assumed, the RNA world hypothesis has a major difficulty. Under those conditions the RNA backbone undergoes rapid cleavage through transesterification. This reaction is accelerated by divalent metal ions, which would have been abundant in aqueous solutions (4,5). Thus, the evolution of RNA sequence complexity must have occurred under conditions in which RNA synthesis was more efficient than random degradation. Since the first ribozymes are likely to have been inefficient, the most straightforward way for RNA synthesis to outpace random degradation would be if conditions were such that degradation was slow. Degradation could have been reduced at low concentrations of divalent metal ions, low temperature, reduced water activity and upon adsorption to surfaces so as to stabilize phosphodiester bonds (4-9). Most of these conditions, and particularly low temperature, may have been available on the early Earth. Indeed, some investigators have argued that at the time of prebiotic evolution much of the water in the oceans was frozen but underwent periodic melting due to large meteor impacts or volcanic activity (8-10). "
Vlassov AV, Johnston BH, Landweber LF, Kazakov SA. Ligation activity of fragmented ribozymes in frozen solution: implications for the RNA world. Nucleic Acids Res. 2004 May 25;32(9):2966-74. Print 2004.

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