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Detection of potential TNA and RNA nucleoside precursors in a prebiotic mixture by pure shift diffusion-ordered NMR spectroscopy.

Islam S, Aguilar JA, Powner MW, Nilsson M, Morris GA, Sutherland JD - Chemistry (2013)

Bottom Line: One potential avenue is the combination of pure shift methodology, in which NMR spectra are measured with greatly improved resolution by suppressing multiplet structure, with diffusion-ordered spectroscopy, in which NMR signals from different species are distinguished through their different rates of diffusion.Such a combination has the added advantage of working with intact mixtures, allowing analyses to be carried out without perturbing mixtures in which chemical entities are part of a network of reactions in equilibrium.The direct formation of potential RNA and TNA nucleoside precursors, amongst other adducts, was observed.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK. saidul.islam@qmul.ac.uk

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a) 1H, and b) 1H-13C HSQC spectra showing the 1H chemical shift region (δ=6.5–7.5 ppm) in which the signals corresponding to 2-aminooxazoline 5 are expected to be seen. Spectrum (b) shows only two chemical shifts for carbon. A 1H-15N HMBC spectrum of the same 1H chemical shift range showed all four peaks with the same 15N chemical shift. The DOSY spectrum (c), however, shows the presence of two different chemical species; that with the greater diffusion coefficient was assigned to compound 5, the other to 14. See the Supporting Information for the full standard DOSY spectrum.
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fig02: a) 1H, and b) 1H-13C HSQC spectra showing the 1H chemical shift region (δ=6.5–7.5 ppm) in which the signals corresponding to 2-aminooxazoline 5 are expected to be seen. Spectrum (b) shows only two chemical shifts for carbon. A 1H-15N HMBC spectrum of the same 1H chemical shift range showed all four peaks with the same 15N chemical shift. The DOSY spectrum (c), however, shows the presence of two different chemical species; that with the greater diffusion coefficient was assigned to compound 5, the other to 14. See the Supporting Information for the full standard DOSY spectrum.

Mentions: When the reaction was carried out in the absence of inorganic phosphate and incubated at an initial pD of 7 at 40 °C, a complex product distribution was observed by 1H NMR spectroscopy (Figure 2 a). To obtain a more complete picture of the chemistry taking place in this mixed oxygenous/nitrogenous system, we attempted to characterise this complex mixture. Because of the outwardly complex nature of the composition, we also considered this mixture to be an ideal candidate for analysis by new pure shift NMR methods,[31–33] alongside an array of standard NMR techniques (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC and 1H DOSY).[34a–f] This is the first time that pure shift diffusion-ordered spectroscopy (DOSY) NMR methodology has been applied to a complex reaction system of partially unknown composition. By using these techniques, we confirmed the direct formation of both TNA nucleoside precursors rac-15 and rac-16 (Scheme 2 b) amongst the products from the reaction of 6 and 7. We believe these preliminary results may have direct implications for the potentially prebiotic assembly chemistry of pyrimidine threonucleotides and TNA.


Detection of potential TNA and RNA nucleoside precursors in a prebiotic mixture by pure shift diffusion-ordered NMR spectroscopy.

Islam S, Aguilar JA, Powner MW, Nilsson M, Morris GA, Sutherland JD - Chemistry (2013)

a) 1H, and b) 1H-13C HSQC spectra showing the 1H chemical shift region (δ=6.5–7.5 ppm) in which the signals corresponding to 2-aminooxazoline 5 are expected to be seen. Spectrum (b) shows only two chemical shifts for carbon. A 1H-15N HMBC spectrum of the same 1H chemical shift range showed all four peaks with the same 15N chemical shift. The DOSY spectrum (c), however, shows the presence of two different chemical species; that with the greater diffusion coefficient was assigned to compound 5, the other to 14. See the Supporting Information for the full standard DOSY spectrum.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3814424&req=5

fig02: a) 1H, and b) 1H-13C HSQC spectra showing the 1H chemical shift region (δ=6.5–7.5 ppm) in which the signals corresponding to 2-aminooxazoline 5 are expected to be seen. Spectrum (b) shows only two chemical shifts for carbon. A 1H-15N HMBC spectrum of the same 1H chemical shift range showed all four peaks with the same 15N chemical shift. The DOSY spectrum (c), however, shows the presence of two different chemical species; that with the greater diffusion coefficient was assigned to compound 5, the other to 14. See the Supporting Information for the full standard DOSY spectrum.
Mentions: When the reaction was carried out in the absence of inorganic phosphate and incubated at an initial pD of 7 at 40 °C, a complex product distribution was observed by 1H NMR spectroscopy (Figure 2 a). To obtain a more complete picture of the chemistry taking place in this mixed oxygenous/nitrogenous system, we attempted to characterise this complex mixture. Because of the outwardly complex nature of the composition, we also considered this mixture to be an ideal candidate for analysis by new pure shift NMR methods,[31–33] alongside an array of standard NMR techniques (1H-1H COSY, 1H-13C HSQC, 1H-13C HMBC and 1H DOSY).[34a–f] This is the first time that pure shift diffusion-ordered spectroscopy (DOSY) NMR methodology has been applied to a complex reaction system of partially unknown composition. By using these techniques, we confirmed the direct formation of both TNA nucleoside precursors rac-15 and rac-16 (Scheme 2 b) amongst the products from the reaction of 6 and 7. We believe these preliminary results may have direct implications for the potentially prebiotic assembly chemistry of pyrimidine threonucleotides and TNA.

Bottom Line: One potential avenue is the combination of pure shift methodology, in which NMR spectra are measured with greatly improved resolution by suppressing multiplet structure, with diffusion-ordered spectroscopy, in which NMR signals from different species are distinguished through their different rates of diffusion.Such a combination has the added advantage of working with intact mixtures, allowing analyses to be carried out without perturbing mixtures in which chemical entities are part of a network of reactions in equilibrium.The direct formation of potential RNA and TNA nucleoside precursors, amongst other adducts, was observed.

View Article: PubMed Central - PubMed

Affiliation: School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK. saidul.islam@qmul.ac.uk

Show MeSH
Related in: MedlinePlus