DsDNA helices

The tertiary structure of DNA is the structural level that is most relevant to 3-D reality. Traditionally, ODNs in a physiologically relevant aqueous solution are considered to be in a random-coiled ssDNA state or in the form of dsDNA helix in the presence of a complementary DNA, including the case of self-complementarity. The double helix is the dominant tertiary structure for biological DNA that can be in one of the three DNA conformations found in nature, A-DNA, B-DNA, and Z-DNA. The B-conformation described by Watson and Crick (11) is believed to predominate in cells (12). However other types of nucleic acid tertiary structures different from random or classical double-stranded helix forms can also be observed. Among them are triplexes, quadruplexes, and several other nucleic acid structures (13, 14). 

Generation of ssDNA is necessary for ensuring that aptamers can fold into unique tertiary structures. In the presence of a complementary strand, a dsDNA helix would form, which hinders selection. The starting material is an ssDNA pool, which is am-... 

The recorded width of the dsDNA helix, for example, when analysed using AFM is typically 12-15 nm, whereas a width of 2 nm is predicted from the crystal structure. For specimens that are approximately circular in cross-section, it is sometimes... 

DNA is a structurally polymorphic macromolecule which, depending on nucleotide sequence and environmental conditions, can adopt a variety of conformations. The double helical structure of DNA (dsDNA) consists of two strands, each of them on the outside of the double helix and formed by alternating phosphate and pentose groups in which phosphodiester bridges provide the covalent continuity. The two chains of the double helix are held... 

The structure of dsDNA makes access of the bases to the electrode surface difficult, hindering their oxidation. The occurrence of DNA damage causes the unwinding of the double helix. As the double helix unwinds, closer access of the bases to the surface is possible, hence they... 

Pabit, S. A., Qiu, X. Y., Lamb, J. S., Li, L., Meisburger, S. P., and Pollack, L. (2009). Both helix topology and counterion distribution contribute to the more effective charge screening in dsRNA compared with dsDNA. Nucleic Acids Res. 37, 3887—3896. 

A very different detection approach was used [40] based on the electro-catalytic oxidation of sugars and amines at a copper electrode surface. The ssDNA and dsDNA were detected in the picomolar concentration range. The electrochemical signal due to dsDNA was higher than due to ssDNA owing to the larger number of easily accessible sugars on the outer perimeter of dsDNA double helix compared to those on a ssDNA of the same size, in contrast to most electrochemical studies based on the electroactivity of the bases. 

DNA consists of two molecules of single-stranded DNA (ssDNA) wrapped together in a fiber called the double stranded helix (dsDNA). Damage can be done to DNA by a number of separate and distinct processes, for example ... 

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