Contribution to the mechanism of the acid-catalyzed hydrolysis of purine nucleosides

Hevesi, L.; Wolfson-Davidson, E.; Nagy, J. B.; Nagy, O. B.; Bruylants, A.

doi:10.1021/ja00768a046

Cited by 77 publications

(47 citation statements)

References 3 publications

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“…195 The departure of the protonated purine 149 and the concomitant formation of the oxonium-carbonium ion 150 were ratelimiting. 194,[196][197][198] The acidic depurination of deoxyadenosine occurred only at very low pH because of the low pKa of protonated N-7 (pKa = -1.48).…”

Section: Exocyclic Amino Function Of Cytosine Adenine and Guanine Numentioning

confidence: 99%

Advances in the Synthesis of Oligonucleotides by the Phosphoramidite Approach

Beaucage¹,

Iyer²

1992

Tetrahedron

692

390

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Section: Exocyclic Amino Function Of Cytosine Adenine and Guanine Numentioning

confidence: 99%

Advances in the Synthesis of Oligonucleotides by the Phosphoramidite Approach

Beaucage¹,

Iyer²

1992

Tetrahedron

692

390

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“…First, we suspected the mechanism to be done to an acidcatalyzed hydrolysis of DNA since it is well known that DNA can be easily damaged by strong acids ͑pH below 2͒. 16 Therefore, we measured the ratios ͑the optical absorption intensity at 260 nm divided by the absorption intensity at 280 nm͒ for DNA and DNA/DWNT solutions prepared at different pH since this ratio has been widely utilized as an indicator for DNA purity. 17 However, we found no distinctive changes in the ratio values, which indicates the absence of C-N cleavages even in strong acidic environments.…”

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confidence: 99%

Diameter-selective separation of double-walled carbon nanotubes

et al. 2008

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Here, we report a simple and effective way of separating double-walled carbon nanotubes as a function of their diameter using individually dispersed nanotube solutions with the aid of long and random single-stranded DNA. The subtle pH change in nanotube solutions gives rise to the preferential coagulation of large-diameter tubes and allows the easy preparation of small-diameter tubes. The stronger van der Waals forces between large-diameter tubes, combined with the decreased solubility of DNA in water at low pH, lead to the preferential agglomeration of large-diameter tubes. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.3039790͔Carbon nanotubes have attracted the attention of scientists as they are considered to be ideal macromolecules exhibiting unique physical and chemical properties that are useful for various potential applications. Since all known synthetic routes for producing nanotubes yield samples containing mixtures of carbon nanotubes with different diameters and chiralities, extensive efforts have been devoted to finding an effective way of producing or isolating particular types of carbon nanotubes. It has been reported that singlewalled carbon nanotubes ͑SWNTs͒ can be effectively sorted using surfactants in conjunction with multiple density gradient ultracentrifuges 1 or by using aromatic polymers. 2 Very recently, LeMieux et al. 3 reported the efficient fabrication of self-sorted and self-assembled SWNT networks for thin-film transistors through the selective deposition of metallic and semiconducting tubes on the controlled surface of a wafer. DNA has also been used as an effective dispersion and separation agent for SWNTs in water on the basis of its ability to wrap itself around the sidewall of carbon nanotubes due to van der Waals attraction between the DNA molecule and the carbon nanotubes. 4,5 Thus, both theoretical and experimental studies have been carried out in order to understand the nature of the interaction between DNA and nanotubes. [6][7][8][9] On the other hand, double-walled carbon nanotubes ͑DWNTs͒ have attracted considerable attention since their intrinsic coaxial structure gives rise to intriguing electronic and optical properties. 10 In addition, these double-walled tubes possess clear advantages over SWNTs for various specific applications such as superior mechanical properties and structural and thermal stability. 11 In the present paper, we present the development, with the aid of optical spectroscopy, of an efficient method for the separation of DWNTs ͑as a function of their diameter͒ by dispersing the DWNTs in solutions of long and random single-stranded DNA ͑ssDNA͒ sequences. The subtle pH change in the DNA/DWNT solutions gives rise to the preferential coagulation of largediameter tubes and allows the easy precipitation of the smalldiameter DWNTs. In addition, flocculated large-diameter tubes can be separated at low pH by using a mild centrifuge and then easily redispersed in a stock DNA solution with a simple vortex mixer. We have found that this separation tech...

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“…This was quite different from the acid-catalyzed hydrolysis of deoxyribonucleosides. 13,14 Consequently, the mechanism of the depyrimidination of polymer 3 was different from that of the acidcatalyzed hydrolysis of nucleosides.…”

Section: Resultsmentioning

confidence: 99%