Purines analysis

Purine analysis can be achieved with this system, specifically inosine (the co-substrate, with phosphate. Scheme 5.5) can be determined quantitatively using similar methodology. The hypoxanthine ratio ([hypoxanthine]/ [hypoxanthine] + [inosine] + [inosine-monophosphate]) is key measure of fish freshness as hypoxanthine is a product of nucleotide degradation and a sign of spoilage. As mentioned previously, hypoxanthine or xanthine... 

Another property of pyrimidines and purines is their strong absorbance of ultraviolet (UV) light, which is also a consequence of the aromaticity of their heterocyclic ring structures. Figure 11.8 shows characteristic absorption spectra of several of the common bases of nucleic acids—adenine, uracil, cytosine, and guanine—in their nucleotide forms AMP, UMP, CMP, and GMP (see Section 11.4). This property is particularly useful in quantitative and qualitative analysis of nucleotides and nucleic acids. 

Saito et al. achieved the first direct confirmation of double alkylation of purine bases by azinomycin B [140]. They incubated azinomycin B with the self-comple-mentary DNA duplex d(TAGCTA)2 and monitored the reaction by HPLC and ion spray MS. They observed initial formation of a monoadduct that was then converted into a crosslinked bisadduct. The crosslink position was identified as between the guanine of one strand and the 5 -adenine on the other strand by thermo-lytic depurination. Further decomposition prevented structural analysis of the azi-... 

Curto R> Voit EO, Cascante M Analysis of abnormalities in purine metabolism leading to gout and to neurological dysfunctions in man. Biochem J 1998 3 29 477. 

Schultz AC, P Nygaard, HH Saxild (2001) Functional analysis of 14 genes that constitute the purine catabolic pathway in Bacillus subtilis and evidence for a novel regulon controlled by the PucR transcription activator. J Bacteriol 183 3293-3302. 

Sequaris J.M.L., Koglin E., Direct analysis of high-performance thin-layer chromatography spots of nucleic purine derivatives by surface-enhanced raman-scattering spectrometry, Anal. Chem. 1987 59 525-527. 

In view of the difficulty of hydrolyzing the pyrimidine nucleosidic linkages, ribonucleic acids have been hydrolyzed to a mixture of purine bases and pyrimidine nucleotides which is then separated by paper chromatography.132, 163 164 This method has been employed extensively for the analysis of ribonucleic acids, and gives reproducible results,166 but it has not been used to any great extent for deoxyribonucleic acids, probably because, under these conditions of hydrolysis, they yield some pyrimidine deoxy-ribonucleoside diphosphates.166... 

Our next step was to assess whether the methodology used to calculate hydration free energy differences for simple carbonyl-containing compounds9 was suitable for heteroaromatic bases. Since our drug design strategy entailed analysis of purine riboside hydration, a series of azanaphthalenes was initially selected for analysis in part because of their structural similarity to purines and in part because of the extensive... 

Some of the impetus for studying tautomeric equilibria in heterocycles arises because of the postulate that point mutations in genetic material may be introduced when a given base exists in a tautomeric form during replication [279, 305-307], Cytosine, in particular, has imino and hydroxy tautomers that are within 3 kcal/mol of the global minimum illustrated above (because of the very large number of possible tautomers for the purines and pyrimidines, only the lowest energy tautomers are presented). This analysis has been made based on a... 

Dobolyi A, Reichart A, Szikra T, SzLlagy N, Kekesi AK, et al. 1998. Analysis of purine and pyrimidine bases, nucleosides and deoxynucleosides in brain microsamples (microdialy-sates and micropunches) and cerebrospinal fluid. Neuro-chem Int 32 247. 

Upon purification of the XDH from C. purinolyticum, a separate Se-labeled peak appeared eluting from a DEAE sepharose column. This second peak also appeared to contain a flavin based on UV-visible spectrum. This peak did not use xanthine as a substrate for the reduction of artificial electron acceptors (2,6 dichlor-oindophenol, DCIP), and based on this altered specificity this fraction was further studied. Subsequent purification and analysis showed the enzyme complex consisted of four subunits, and contained molybdenum, iron selenium, and FAD. The most unique property of this enzyme lies in its substrate specificity. Purine, hypoxanthine (6-OH purine), and 2-OH purine were all found to serve as reductants in the presence of DCIP, yet xanthine was not a substrate at any concentration tested. The enzyme was named purine hydroxylase to differentiate it from similar enzymes that use xanthine as a substrate. To date, this is the only enzyme in the molybdenum hydroxylase family (including aldehyde oxidoreductases) that does not hydroxylate the 8-position of the purine ring. This unique substrate specificity, coupled with the studies of Andreesen on purine fermentation pathways, suggests that xanthine is the key intermediate that is broken down in a selenium-dependent purine fermentation pathway. ... 

The analysis of a variety of compounds of biochemical interest have been reported. Some of these were given in the preceding section. The versatility of RPC can be shown, however, by considering the large number of applications given to the analysis of purine and pyrimidine bases, their nucleosides and nucleotides, as well as the determination of amino acids and their corresponding peptides and proteins. 

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