NMR Studies of Purines

Dračínský, Martin; Pohl, Radek

doi:10.1016/b978-0-12-800184-4.00002-3

Cited by 20 publications

(23 citation statements)

References 206 publications

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“…Interestingly, the 13 C spectrum showed only seven aromatic signals, even though the compound has eight carbons that should appear in the aromatic region (100–200 ppm). Therefore, a 13 C‐APT NMR experiment was carried out to resolve possible peak overlaps . Figure a shows the expanded portion of 13 C and 13 C‐APT resolving the peaks closely residing at 159.87 ppm (negative) and 159.85 ppm (positive), corresponding to C–H and quaternary C, respectively.…”

Section: Resultsmentioning

confidence: 81%

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Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder

Walalawela

Urrutia

Thomas

et al. 2019

Photochem & Photobiology

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In order to develop a new long alkane chain pterin that leaves the pterin core largely unperturbed, we synthesized and photochemically characterized decyl pterin‐6‐carboxyl ester (CapC) that preserves the pterin amide group. CapC contains a decyl‐chain at the carboxylic acid position and a condensed DMF molecule at the N2 position. Occupation of the long alkane chain on the pendent carboxylic acid group retains the acid–base equilibrium of the pterin headgroup due to its somewhat remote location. This new CapC compound has relatively high fluorescence emission and singlet oxygen quantum yields attributed to the lack of through‐bond interaction between the long alkane chain and the pterin headgroup. The calculated lipophilicity is higher for CapC compared to parent pterin and pterin‐6‐carboxylic acid (Cap) and comparable to previously reported O‐ and N‐decyl‐pterin derivatives. CapC's binding constant Kb (8000 M−1 in L‐α‐phosphatidylcholine from egg yolk) and ΦF:Φ∆ ratio (0.26:0.40) point to a unique triple function compound, although the hydrolytic stability of CapC is modest due to its ester conjugation. CapC is capable of the general triple action not only as a membrane intercalator, but also fluorophore and 1O2 sensitizer, leading to a “self‐monitoring” membrane fluorescent probe and a membrane photodamaging agent.

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Section: Resultsmentioning

confidence: 81%

“…1 H, 13 C, 13 C‐APT and 2D NMR spectra were recorded on a Bruker 400 MHz NMR spectrometer. 13 C‐APT NMR was carried out based on the technique described elsewhere .…”

Section: Methodsmentioning

confidence: 99%

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder

Walalawela

Urrutia

Thomas

et al. 2019

Photochem & Photobiology

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“…The presence of C8-H1’ and C1’- H8 correlations in the HMBC spectrum allowed for the identification of two of three samples as either N 7 (6) or N 9- (5) ribosides. The former riboside (6) was identified by the presence of C6- H1’ and C6-H8 correlations, where C6 was assigned based on its relatively low chemical shift (typical values and the substituent effects have been reviewed in Reference [34]), compared to the expected chemical shift of C4. By elimination, the remaining sample was identified as the N 9-riboside (5), in agreement with chemo-enzymatic identification provided in the previous paragraph.…”

Section: Resultsmentioning

confidence: 99%

Tri-Cyclic Nucleobase Analogs and Their Ribosides as Substrates of Purine-Nucleoside Phosphorylases. II Guanine and Isoguanine Derivatives

Stachelska-Wierzchowska

Wierzchowski

Górka

et al. 2019

Molecules

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Etheno-derivatives of guanine, O6-methylguanine, and isoguanine were prepared and purified using standard methods. The title compounds were examined as potential substrates of purine-nucleoside phosphorylases from various sources in the reverse (synthetic) pathway. It was found that 1,N2-etheno-guanine and 1,N6-etheno-isoguanine are excellent substrates for purine-nucleoside phosphorylase (PNP) from E. coli, while O6-methyl-N2,3-etheno-guanine exhibited moderate activity vs. this enzyme. The latter two compounds displayed intense fluorescence in neutral aqueous medium, and so did the corresponding ribosylation products. By contrast, PNP from calf spleens exhibited only modest activity towards 1,N6-etheno-isoguanine; the remaining compounds were not ribosylated by this enzyme. The enzymatic ribosylation of 1,N6-etheno-isoguanine using two forms of calf PNP (wild type and N243D) and E. coli PNP (wild type and D204N) gave three different products, which were identified on the basis of NMR analysis and comparison with the product of the isoguanosine reaction with chloroacetic aldehyde, which gave an essentially single compound, identified unequivocally as N9-riboside. With the wild-type E. coli enzyme as a catalyst, N9--d- and N7--d-ribosides are obtained in proportion ~1:3, while calf PNP produced another riboside, tentatively identified as N6--d-riboside. The potential application of various forms of PNP for synthesis of the tri-cyclic nucleoside analogs is discussed.

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“…145 Hz) for the delays may lead to a low or zero intensity of the C8 carbon signals. 30 Nowadays, 2D correlation NMR techniques are the core of the NMR structure investigation of organic molecules, mainly homonuclear correlation spectroscopy (COSY) experiments, heteronuclear HSQC or HMQC experiments, where crosspeaks indicate one-bond H−C or H−N correlations, and heteronuclear multiple-bond correlation (HMBC) experiments, where two-, three-and multiple-bond correlations can be detected.…”

Section: ■ Struggle For Sensitivitymentioning

confidence: 99%

“…Nitrogen chemical shifts and coupling constants can be used for the determination of regiochemistry, protonation state of substituted bases, and intermolecular interactions, such as hydrogen bonding. 30 Experiments based on the nuclear Overhauser effect (NOE) provide information on the spatial proximity of atoms. Homonuclear H,H-NOE experiments are commonly used in the structure determination of covalent adducts.…”

Section: ■ Struggle For Sensitivitymentioning

confidence: 99%

Determination of the Nucleic Acid Adducts Structure at the Nucleoside/Nucleotide Level by NMR Spectroscopy

Dračínský

Pohl

2015

Chem. Res. Toxicol.

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All living organisms are exposed to xenobiotics from the environment. The exposure can lead to the formation of covalent adducts of xenobiotics or their metabolites with nucleic acids (NAs).The knowledge of NA adduct structure provides valuable information n the mechanism of carcinogenesis on a molecular level. While NMR spectroscopy is extremely successful in structural analysis of many classes of molecules ranging from small inorganic and organic molecules to large biomacromolecules, the structural analysis of NA adducts by NMR spectroscopy is accompanied by some challenges. First, the structural diversity of the adducts is very large; the electrophilic species generated from the metabolism of xenobiotics can attack various atoms of the nucleobases, and new rings are frequently formed. The second challenge in the DNA adducts structure determination is the low sensitivity of NMR spectroscopy and low amount of the adducts isolated from in vivo experiments. Recent developments of NMR hardware and experimental methods have led, however, to unprecedented sensitivity. This contribution reviews NMR techniques that are commonly applied in the determination of nucleic acid adducts structure at the nucleoside/nucleotide level. These NMR techniques and the large structural heterogeneity of NA adducts are demonstrated on recent examples (mostly published after 2000) of NA adducts structure determined by NMR. Most of the examples report 2′-deoxyribonucles(t)ide derivatives, but RNA adducts are also briefly discussed. The influence of the formation of NA adducts on nucleoside conformation (particularly syn/anti orientation of the base) is also demonstrated on recent examples.

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NMR Studies of Purines

Cited by 20 publications

References 206 publications

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder

Tri-Cyclic Nucleobase Analogs and Their Ribosides as Substrates of Purine-Nucleoside Phosphorylases. II Guanine and Isoguanine Derivatives

Determination of the Nucleic Acid Adducts Structure at the Nucleoside/Nucleotide Level by NMR Spectroscopy

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NMR Studies of Purines

Cited by 20 publications

References 206 publications

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, 1O2 Sensitizer and Membrane Binder

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, 1O2 Sensitizer and Membrane Binder

Tri-Cyclic Nucleobase Analogs and Their Ribosides as Substrates of Purine-Nucleoside Phosphorylases. II Guanine and Isoguanine Derivatives

Determination of the Nucleic Acid Adducts Structure at the Nucleoside/Nucleotide Level by NMR Spectroscopy

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Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, ¹O₂ Sensitizer and Membrane Binder