2140-64-9Relevant academic research and scientific papers
Noncanonical RNA Nucleosides as Molecular Fossils of an Early Earth—Generation by Prebiotic Methylations and Carbamoylations
Schneider, Christina,Becker, Sidney,Okamura, Hidenori,Crisp, Antony,Amatov, Tynchtyk,Stadlmeier, Michael,Carell, Thomas
supporting information, p. 5943 - 5946 (2018/04/30)
The RNA-world hypothesis assumes that life on Earth started with small RNA molecules that catalyzed their own formation. Vital to this hypothesis is the need for prebiotic routes towards RNA. Contemporary RNA, however, is not only constructed from the four canonical nucleobases (A, C, G, and U), it also contains many chemically modified (noncanonical) bases. A still open question is whether these noncanonical bases were formed in parallel to the canonical bases (chemical origin) or later, when life demanded higher functional diversity (biological origin). Here we show that isocyanates in combination with sodium nitrite establish methylating and carbamoylating reactivity compatible with early Earth conditions. These reactions lead to the formation of methylated and amino acid modified nucleosides that are still extant. Our data provide a plausible scenario for the chemical origin of certain noncanonical bases, which suggests that they are fossils of an early Earth.
Methylation of Nucleosides with Trimethylsulfonium Hydroxide. Effects of Transition Metal Ions
Yamauchi, Kiyoshi,Nakagima, Toru,Kinoshita, Masayoshi
, p. 3865 - 3868 (2007/10/02)
The effect of transition metal acetylacetonates on the methylation of ribo- and deoxyribonucleosides with trimethylsulfonium hydroxide was studied.With ribonucleosides the metal complexes promoted O'-methylation at the 2' and 3' positions of the ribosyl group.A comparable effect was not observed in methylation of deoxyribonucleosides.These results are attributed to an increase in the nucleophilicity of the 2'-OH and 3'-OH groups of the ribosides through complex formation with the metal ion; such a complex cannot form with the deoxyribose derivatives.The activity of the metal ions studied for promoting this O'-methylation increased in the order Mn2+ 2+ = Zn2+ 2+ 2+ 3+.These M(AA)n also suppressed N-methylation of the purine and pyrimidine rings of adenosine and cytidine.It is suggested that this result may be caused by coordination of the metal ions with ring nitrogens.
Methylation study of ribonucleosides, deoxyribonucleosides, and 2′-O-methylribonucleosides with trimethylsulphonium hydroxide and trimethylsulphonium iodide. Influence of the 2′-hydroxy-groups on the reactivity of the base moieties of ribonucleosides
Yamauchi, Kiyoshi,Nakagima, Toru,Kinoshita, Masayoshi
, p. 2787 - 2792 (2007/10/02)
Methylations of the naturally occuring ribonucleoside (1), deoxyribonucleoside (2), and 2′-O-methylribonucleoside (3) were carried out using trimethylsulphonium hydroxide (Me3SOH) and trimethylsulphonium iodide (Me3Sl). The base moiety of (2) and (3) are more reactive than the corresponding base moiety of (1). The sites and extent of methylation of (2) are considerably different from those of (1), but are almost identical with those of (3). The reactivities of (1)-(3) are discussed in connection to an intramolecular interaction of the 2′-OH groups with the base moiety of (1). The methylating characteristics of Me 3SOH and Me3Sl are also described. The kinetics indicate an SN2 mechanism for methylation of nucleosides by Me 3S+ ions.
Unusual Competition between Nitrogen and Carbon Methylation of Nucleosides by Methyl Radical in Various Aqueous Media
Zady, Mona F.,Wong, John L.
, p. 2373 - 2377 (2007/10/02)
Five nucleosides, adenosine, guanosine, cytidine, thymidine, and uridine, were allowed to react with methyl radical produced by homolysis of tert-butyl peracetate.The extent and sites of reaction exhibited a marked dependence on the pH of the aqueous medium.In the region of pH 1-4, the major products arose from C-methylation of the nucleosides.The purines were more reactive than the pyrimidines under these acidic conditions.In the pH range of 4-10, the extent of C-methylation decreased steadily with increasing pH while N-methylated products arising from methylationof the ring nitrogen and/or exocyclic amino groups predominated.In this pH range, the pyrimidine nucleosides were the more reactive.Beyond pH 10, the extent of methylation diminished in all cases as decomposition of tert-butyl peracetate became rampant.The C-methylation occurs by way of an addition mechanism while N-methylation appears to proceed via radical abstraction of a hydrogen from the N-H group followed by combination with methyl radical.The implications of these reactivity and methylation patterns in radical carcinogenesis are discussed.
