Quantitative Determination of Nucleic Acids

Applications. Bathophenanthroline and transition metal complexes with bathophenanthroline as ligand are compounds that exhibit interesting photophysical and photochemical properties for the application in dye-sensitized solar cells or OLEDs. Further, metal-bathophenanthroline complexes can be used for the quantitative determination of nucleic acids. 

Lanthanide labels have also been used for the determination of nucleic acids. Eu chelates can be coupled to DNA probes that can be used to quantitate DNA... 

Not very well, but he was my big competitor when I was a graduate student. My thesis research at UCLA was to develop methods to analyze purines and pyrimidines, which are the basic constituents of nucleic acids. The old methods were just terrible, not quantitative and very slow. Finally, I realized that I could use microbiological methods and determine the three pyrimidine bases. I did that and it worked. I never could find bacteria that were specific for the purines. If I had gotten that to work, I would have beaten Chargaff, but just after I had developed this methodology, he came out with his chromatographic methods. Then he was able to determine the ratio of the bases and show that they were not all present... 

The triphenylmethcuie dye, aurintricarboxylic acid (ATA), whose commonly accepted structure is shown in Figure 1, is a potent inhibitor of protein nucleic acid interactions. First employed by the metals industry for the quantitative determination of the aluminion ion (1), this dye in recent years has been utilized extensively by molecular... 

The most widespread use of UV and visible spectroscopy in biochemistry is in the quantitative determination of absorbing species (chromophores), known as spectrophotometry. All spectrophotometric methods that measure absorption, including various enzyme assa3rs, detection of proteins, nucleic acids and different metabolites, reside upon two basic rules, which combined are known as the Beer-Lambert law. Lambert s law states that the fraction ofli t absorbed by a transparent medium is independent of the incident li intensity, and each successive layer of the medium absorbs an equal fraction of the li t passing throu it. This leads to an exponential decay of the light intensity along the light path in the sample, which can be expressed mathematically, as follows ... 

The grafting of nucleic acid base derivatives with a hydroxyl group onto poly(ethyleneimine) polymer backbone was also carried out by the activated ester method. Since the reactivity of the lactone is low, the direct reaction of the lactone derivative with poly(ethyleneimine) was not effective. Therefore, the lactone derivatives were at first hydrolyzed to the 3-hydroxybutyric acid derivatives, followed by condensation with poly(ethyleneimine) using the activated ester method. The grafting reaction was carried out in N,N-dimethylformamide, where a small amount of 4-pyrrolidinopyridine was added as an effective catalyst. Nucleic acid base contents of the polymers were determined by UV spectroscope of hydrolyzed samples. A quantitative calculations were made by using the corresponding carboxyethyl derivatives as standards. The nucleic acid base units (unit mol%) on the polymer are tabulated in Table 1. 

Ionic interactions are also used to associate genetic material with nanoparticulate carriers. Electrophoresis is perhaps the easiest way to assess the association efficiency of nucleic acids to a nanostructure. The associated genetic material will not migrate in an electrophoresis gel as would happen with free nucleic acids. It is also useful to visually determine the conformation of the plasmid DNA, supercoiled being the most effective form in comparison to circular and open forms. The association efficiency can be quantitatively determined using commercial kits and fluorescence techniques or, directly but with a lower sensitivity, by UV determination. For this purpose, the free nucleic acid needs to have been previously separated and subsequently quantified. 

Immobilization of the nucleic acid base derivatives on silica gel was confirmed by IR spectra and elementary analysis, and hydrolysis followed by measurement of UV spectra. The IR spectra for Si-Hyp suggested the presence of hypoxanthine units in the silica gel derivative. Quantitative determination of the content of hypoxanthine units in Si-Hyp was done by hydrolysis of the silica gel derivative followed by measurement of UV spectra bases on the spectra of the carboxyethyl derivative of hypoxanthine (14). The content of the hypoxanthine units in the silica gel derivative was about 1.5 x 10" mol/g. 

Biomolecular MS and in particular MALDI-TOF-MS (see Sections 2.1.22 and 2.2.1) permit the routine analysis of oligonucleotides up to 70-mers, intact nucleic acids, and the direct detection of DNA products with no primer labels with an increase in analysis speed and mass accuracy especially in contrast to traditional DNA separation techniques such as slab gels or capillary electrophoresis. Applications focus on the characterization of single nucleotide polymorphisms (SNPs) and short tandem repeats (STRs). Precise and accurate gene expression measurements show relative and absolute numbers of target molecules determined independently of the number of PCR cycles. DNA methylation can be studied quantitatively. 

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