Oxidation of adenine and guanine
Reaction of purine bases of DNA by hydroxyl radicals 8 and adenine (O8A) 8 – can lead to the formation oxo-guanine (O8G) (Figure 10). 8 These databases – exists mainly in the keto form, which is the subject of great interest to contribute to mutagenesis. Directly provides an opportunity pairing based erroneous whereby changes in eight positions Watson – was formed Crick base pairs, but in order to increase the tendency of them to adopt a son conformation and the presence of oxygen bulky It does not affect the function of guanine and adenine. It is possible to bring the G base pairs with T mutation tranversion · Blue via O8G that O8G the presence of a base of genomic DNA: anti configuration is stabilized (Fig. 11) InterBase of two hydrogen bonds. In addition to having a thermodynamic stability reasonable, therefore O8G, combines the base of the sugar, pseudosymmetric · pairs N-glydosidic link Watson – are structurally similar to the Crick base pairs. Similarity of the two thymine bases 8 oxygen atoms · T base pairs O8G – is particularly noticeable in the minor groove at the position to be occupied by an oxygen atom. Therefore, knowing the enzyme O8G · base pair is correct is not easy.
Unlike O8G, O8A (8 – hydroxy-adenine) are mutagenic: Highly remains strong preference for thymine as partners adenine base that has changed. Can be the origin structural primarily, mismatches most thermodynamically stable, the O8A · G, pudding If it is asymmetrical This preference, – structure and pyrimidine mismatch is similar; O8A · Therefore, G is likely to be an easy target for the repair enzymes. In order to appear to be held together (branched-chain hydrogen bonds often, and is referred to as Figure 12) 3 oriented hydrogen bonds and four, G (green) O8A (anti) base pairs (Fig. 12) is important it some. It guanine, 2 – by reacting with the oxygen atom of O8A, to be adjacent to (not shown in FIG 12) one water molecule to perform capacitive hydrogen bonds and possible, this structure is an amino group , is stable. As mentioned above, any form of base pairs, guanine hydrogen bonds perform potential 2 – In contrast, compared with the unpaired bases individual interference with the amino group and the base water molecules adjacent or tend to be unstable with. Adenine and 8 – 8 – oxo-guanine base is restored in base excision repair pathway.
Been studied in an aqueous medium using detergent-, high purity graphene commercially available have not been modified in any way chemically electrochemical oxidation of guanine and adenine contrast to pyrolysis end surface changes in the graphite electrode graphite is a basis (EPPG), basal plane pyrolytic graphite and (BPPG),. It is reduced in terms of the peak height of the electrochemical oxidation potential generated by the high oxidation potential is BPPG main electrode of the electrode that was modified electrochemical oxidation graphene adenine, observation voltammetric response. Shows the voltammetric signal which is improved compared with the control experiments using graphite electrodes which are modified to reduce the oxidation potential was observed as compared to bare ground electrode BPPG. In addition to the confirmation is consistent and strong literature reports of these, to those found in EPPG that BPPG is very important, the density of the portion of the edge surface, such a response.
To its unique structure, the reduction reaction of graphene modified electrode is due to the graphene at low density electricity (end face) site. In the case of electrochemical oxidation of guanine, interestingly, voltammetric response less interesting exhibits showed a decrease in the oxidation potential than the main electrode BPPG in view of the ground electrode height versus graphene electrode peaks changed. You can be attracted to the principal plane site easily According to the report of literature, such a response is due to the unique structure of graphene as the base surface of the large stock of adsorption, of guanine. But, unfortunately, the graphene, plane, which accounts for reduction voltammetry response, density of nearby objects is low. Furthermore, studies of the execution pH dependent chemical irreversible as compared to the observed in graphite electrodes to suggest graphene in both the guanine and adenine with an electrode that is BPPG graphene change showing the same number of electron transfer to protons and Before the typical step, do not change the electrochemical mechanism. Critically, in a study of the reliability of the plane question DNA bases have been found unacceptable analytically modification of the electrode surface and graphene, overall graphene electrode density of objects near the use of the future is low while reducing the speed of reaction Na.
Electrochemical sensors of adenine for guanine and has been developed using cyclodextrin-modified poly carbon paste electrode (N-acetyl aniline) of (PNAANI). The oxidation mechanism of adenine and guanine of the electrode surface, I was examined by cyclic voltammetry. In addition, I have included was found to be irreversible, electrode process is pH-dependent, the reaction product of a few. Method of electron transfer is carried out in a continuous process with the formation of the intermediate is strongly adsorbed on the surface of the electrode. In addition, a new method for evaluation of formation constant apparent cyclodextrin immobilized adenine and guanine, was reported by changing the surface coverage of the test specimens. Adenine and guanine showed a concentration of linear ranging from 0.1 to 10 micro-M by using the experimental detection limit differential pulse voltammetry and 0.05μM. Linear concentration range of adenine 2-150 6-104 micromolar and micromolar guanine was found in cyclic voltammetry was used to determine the analyte both.
After prepared using the ionic liquid (BPPF (6)) of N-butyl-pyridinium hexafluorophosphate as a binder, the carbon electrode ionic liquid (CILE) is used for the simultaneous detection of adenine and guanine. Was considered to Zille carefully Elektrookislenie direct behavior of guanine and adenine. The results, negative change will increase the oxidation potential peaks guanine and adenine shows the oxidation peak current, it is shown that different carbon paste electrode with a conventional (CPE). Electrical parameters of guanine and adenine CILE are calculated, respectively, a new electrical analysis method is designed for the detection of adenine and guanine. I show a good behavior in the simultaneous detection of guanine and adenine with partition coefficient as 0.304V in Zille. Performs further dimension single-stranded DNA was heat denatured (ssDNA), was calculated as 0.81 the value of single-stranded DNA of (G+ C) / (A + T).