36597-25-8Relevant articles and documents
Investigations of electron-transfer reactions and the redox mechanism of 2′-deoxyguanosine-5′-monophosphate using electrochemical techniques
Goyal, Rajendra N.,Sondhi, Sham M.,Lahoti, Anand M.
, p. 587 - 595 (2007/10/03)
Electron-transfer reactions of 2′-deoxyguanosine-5′- monophosphate (dGMP) have been investigated in phosphate buffers of different pH at a pyrolytic graphite electrode (PGE). In cyclic voltammetry, two well-defined oxidation peaks, 1a (pH 1.9-1
Further insights into the electrooxidation of N-methyluric acids and correlation of oxidation potentials with frontier MO energies
Goyal, Rajendra N.,Thankachan,Jain, Neena
, p. 1515 - 1524 (2007/10/03)
The electrochemical oxidation of various N-methylated uric acids has been studied at a pyrolytic graphite electrode at physiological pH 7.2. The observed behavior was compared with uric acid to evaluate the effect of a methyl group. The E(p) value was found to shift to less positive potentials when a methyl group is present at the N-1 position and to more positive potentials when substitution is at the N-3 position or at nitrogens of the imidazole ring. The values of ΔE(p) followed the additivity of the substituents effect only when two methyl groups are present in different rings. The methyl groups were also found to increase the electron density at N atoms of uric acids, and an excellent correlation between the oxidation potential and energy of the highest occupied molecular orbital was observed. On the basis of these studies it is concluded that the presence of a methyl group in the pyrimidine ring restricts the formation of allantoin. The peroxidase-catalysed oxidation of the N-methylated derivatives of uric acid was found to follow a pathway similar to that observed during electrochemical oxidation.
Electrochemical and peroxidase catalysed oxidation of 9-β-D-ribofuranosyluric acid 5′-monophosphate
Goyal, Rajendra N.,Rastogi, Arshi
, p. 2423 - 2429 (2007/10/03)
The electrochemical oxidation of 9-β-D-ribofuranosyluric acid 5′-monophosphate (UA-9R-5′-P) in aqueous solution has been studied in the pH range 2.10-10.0. The evidence strongly indicates that UA-9R-5′-P is oxidized in a 2e-, 2H+ reaction to give an unstable diimine which subsequently decomposes. A UV absorbing intermediate is observed during electrooxidation which decays in a pseudo first-order reaction to give alloxan, urea and ribosyl phosphate at pH 3.0. Controlled potential electrolysis results in the transfer of 2.0 ± 0.2 electrons per molecule and three major products are obtained at pH 7.0; allantoin, 5-hydroxyhydantoin-5-carboxamide and D-ribose. Tentative reaction schemes are proposed to explain the formation of these products. Oxidation of UA-9R-5′-P in the presence of peroxidase and H2O2 also generates an intermediate which has spectral and kinetic properties identical to those of the intermediate generated electrochemically. Thus, it is believed that electrochemical and enzymic oxidation of UA-9R-5′-P proceed by identical reaction mechanisms.
Comparison of Electrochemical and Enzymic Oxidation of 3-Methyluric Acid
Goyal, Rajendra N.,Verma, Madhu Shri
, p. 1241 - 1248 (2007/10/02)
The electrochemical oxidation of 3-methyluric acid has been studied in the pH range 3.2-11.3 at pyrolytic graphite and glassy carbon electrodes.The conjugate base is the species oxidized over the whole pH range studied.Intermediates generated have been characterized in terms of their UV spectra and kinetics of decay, and products have been separated and characterized.The intermediates, formed and spectral and kinetics studies, during the peroxidase-catalysed oxidation of 3-methyluric acid indicated identical behaviour to that observed in electrochemical oxidation.It has thus been concluded that the electrochemical and enzymic oxidation of 3-methyluric acid proceed by an identical EC mechanism.
On-line electrochemistry/thermospray/tandem mass spectrometry as a new approach to the study of redox reactions: the oxidation of uric acid.
Volk,Yost,Brajter-Toth
, p. 1709 - 1717 (2007/10/02)
The electrochemical oxidation pathway of uric acid was determined by on-line electrochemistry/thermospray/tandem mass spectrometry. Intermediates and products formed as a result of electrooxidation were monitored as the electrode potential was varied. Several reaction intermediates have been identified and characterized by tandem mass spectrometry. The tandem mass spectrometric results provide convincing evidence that the primary intermediate produced during the electrooxidation of uric acid has a quinonoid diimine structure. The results indicate that once formed via electrooxidation, the primary intermediate can follow three distinct reaction pathways to produce the identified final products. The final electrochemical oxidation products observed in these studies were urea, CO2, alloxan, alloxan monohydrate, allantoin, 5-hydroxyhydantoin-5-carboxamide, and parabanic acid. The solution reactions that follow the initial electron transfer at the electrode are affected by the vaporizer tip temperature of the thermospray probe. In particular, it was found that at different tip temperatures either hydrolysis or ammonolysis reactions of the initial electrochemical oxidation products can occur. Most importantly, the results show that the on-line combination of electrochemistry with thermospray/tandem mass spectrometry provides otherwise difficult to obtain information about redox and associated chemical reactions of biological molecules such as the structure of reaction intermediates and products, as well as providing insight into reaction pathways.
