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Intrinsic DNA fluorescence is the fluorescence emitted directly by DNA when it absorbs ultraviolet (UV) radiation. It contrasts to that stemming from fluorescent labels that are either simply bound to DNA or covalently attached to it, [1] [2] widely used in biological applications; such labels may be chemically modified, not naturally occurring, nucleobases.
Contamination by phenol, which is commonly used in nucleic acid purification, can significantly throw off quantification estimates. Phenol absorbs with a peak at 270 nm and a A 260/280 of 1.2. Nucleic acid preparations uncontaminated by phenol should have a A 260/280 of around 2. [2]
Nucleic acids present in the washed (and preferably dried) silica-nucleic acid complexes is eluted into chosen elution buffer such as TE buffer, aqua bidest, and so on. The selection of the elution buffer is co-determined by the contemplated use of the isolated nucleic acid. In this way, pure nucleic acids are isolated from the starting material.
A typical molecular beacon structure can be divided in 4 parts: 1) loop, an 18–30 base pair region of the molecular beacon that is complementary to the target sequence; 2) stem formed by the attachment to both termini of the loop of two short (5 to 7 nucleotide residues) oligonucleotides that are complementary to each other; 3) 5' fluorophore ...
Nucleic acids have a smaller percentage of hydrogen atoms, which are the atoms usually observed in NMR, and because nucleic acid double helices are stiff and roughly linear, they do not fold back on themselves to give "long-range" correlations. [3] The types of NMR usually done with nucleic acids are 1 H or proton NMR, 13 C NMR, 15 N NMR, and ...
The nucleic acid notation currently in use was first formalized by the International Union of Pure and Applied Chemistry (IUPAC) in 1970. [1] This universally accepted notation uses the Roman characters G, C, A, and T, to represent the four nucleotides commonly found in deoxyribonucleic acids (DNA).
19 F NMR is also useful if nonnatural nucleotides such as 2'-fluoro-2'-deoxyadenosine are incorporated into the nucleic acid strand, as natural nucleic acids do not contain any fluorine atoms. [2] [4] 1 H and 31 P have near 100% natural abundance, while 13 C and 15 N have low natural abundances. For these latter two nuclei, there is the ...
These nucleotides are known as 5-(3-aminoallyl)-nucleotides since the aminoallyl group is usually attached to carbon 5 of the pyrimidine ring of uracil or cytosine. The primary amine group in the aminoallyl moiety is aliphatic and thus more reactive compared to the amine groups that are directly attached to the rings ( aromatic ) of the bases.