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作者：非文人 在 罕见奇谈 发贴, 来自 http://www.hjclub.org
现在后一个问题有较多证据证实，而前一个问题基本没解决。
Orgel, Leslie E
Hydrolysis of RNA on Solid Surfaces.
(a). Inorganic
The hypothesis that an RNA world, that is a biology based on an RNA genetic system that did not involve coded proteins, is now rather generally accepted. The stability of RNA thus becomes a central issue in theories of the origins of life. RNA hydrolysis in aqueous solution has been studied in detail. However, we are unaware of any published work on the hydrolysis of RNA on the surfaces of abundant minerals. Since much prebiotic chemistry is thought to have taken place on such surfaces, this is a serious omission. We have undertaken a series of experiments to fill this gap.
We used tRNAphe as our substrate because it is available commercially in a state of high purity. We use [ 32 P] - labeling in association with gel electrophoresis to monitor hydrolysis. This has the advantage that the positions of hydrolysis, as well as the overall extent of hydrolysis, are readily measured.
Many common minerals turn out to be effective catalysts for the hydrolysis of tRNA phe. . It is not surprising that tRNA is hydrolyzed rapidly on the surface of Pb2 +containing minerals (Fig 1) such as galena (PbS) or lead phosphate since the Pb2 + ion in solution is already known to be an effective catalyst for the hydrolysis of RNA in homogeneous aqueous solution. However, it is surprising that calcium-containing minerals such as hydroxylapatite are also effective catalysts (Fig. 2) while Ca2 + in aqueous solution is not. Our experiments emphasize that any theory of the origin of biopolymers that relies on surface catalysis, must also take into account the effect of surface hydrolysis.
(b). Organic
In parallel studies we found that suspensions of a variety of moderately soluble organic compounds such as glutamic acid and histidine are very effective and sometimes sequence-specific catalysts for the hydrolysis of
tRNA phe . The intensity of hydrolysis and the positions of the most sensitive phosphodiester bonds are strongly dependent on the structure of the molecule involved; b -glutamic acid, for example, is a much more effective catalyst than a -glutamic acid. The reaction is often enantiospecific, that is the suspensions of D- and L- enantiomers of the same aminoacid may catalyze hydrolysis of tRNA phe at very different rates.
Kozlov, Igor A.; Orgel, Leslie E (in press) "Oligomerization of deoxyguanosine 5’phosphoro-2-methylimidazolide on a polycytidylate template" Origins Life Evol. Biosphere,29: 593-595
Kozlov I.; Zielinski, M,; Allart, B.; Kerremans, L.; Van Aerschot, A.; Busson, R.; Herdewijn, P.; Orgel, L.E. (2000) "Nonenzymatic template-directed reactions on altritol oligomers, pre-organized analogues of oligonucleotides" Chemistry-A European Journal,6: 151-155
Gao, Kui and Orgel, Leslie E. (2000) "Polyphosphorylation and non-enzymatic template-directed ligation of oligonucleotides" Origins Life Evol. Biosphere,30: 45-51.
Maurel, Christine-Marie and Orgel, Leslie E. (2000) "Oligomerization of a -thioglutamic acid" Origins of Life Evol. Biosphere, 30: 423-430.
Gao, K.; Orgel, L.E. (2000) ‘A convenient synthesis of a novel nucleoside analogue: 4-(a -diformyl-methyl)-1-(b -D-ribofuranosyl)-2-pyrimidinone.’ Nucleosides and Nucleotides, 19: 935-940.
Zielinski, M.; Kozlov, I.; Orgel, L.E. (2000)‘A comparison of RNA with DNA in Template-Directed Synthesis’. Helvetica Chem Acta 83: 1678-1684.
Orgel, L.E. (2001) ‘The origin of biological information.’ Proceedings of the 11th Annual CSEOL Symposium, April 7, 2000, Publication XXX, 2001.
Kozlov I.; Orgel, L.E.; Nielsen, P.E. ‘Remote enantio selection transmitted by an achiral PNA backbone’. Angewandte Chemie, XX: xxx-yyy.
Kozlov I.; Orgel, L.E. (2000) ‘Nefermentativnyi matricno-napravlennyi sintez RNK’. Molekularnaya Biologlya (in Russian), 34 (6), 1-10.
Orgel, L.E. (2000) ‘Self-organizing biochemical cycles.’ Proc. Nat’l. Acad. Sci. U.S.A.,97: 12503-12507.
Wen, K; Han, H.; Hoffman, T. Z.; Janda, K. D.; Orgel, L. E. (2000) ‘The synthesis of b -peptides containing guanidino groups’, Bioorganic & Medicinal Chemistry Letters, XX: xxx-yyy.
Wen, K; Orgel, L. E. (2000) ‘The specificity of peptide chain extension by N-carboxyanhydrides’, Origins Life Evol. Biosphere, XX: xxx-yyy.
作者：非文人 在 罕见奇谈 发贴, 来自 http://www.hjclub.org |
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