Triple helical nucleic acid structures

Triple helical nucleic acid structures are formed by the binding of a third strand in the major groove of a WC basepaired duplex. The formation of triple helical structure was first reported in 1957 for the poly-r(A).poly-r(U) sequences [17], wherein it was proposed that a second poly-r(U) strand could... 

Investigations to elucidate the formation of higher-order nucleic acid structures were also done by Wang et al. [68]. Triple-helical nucleic acid formation in solution, in particular C GC and G GC, followed by immobilization of the nucleic acid complex onto electrode surfaces of mercury and carbon paste was elucidated by reductions in the magnitude of the guanine oxidation peak and disappearance of a... 

Choice of a buffer with an appropriate pK to give sufficient buffer capacity at the desired pH is important to prevent changes in pH as a result of a nucleic acid structural transition. Since nucleic add concentrations for UV melting studies are routinely 10" to 10" m and most nucleic add structural transitions do not involve the absorption or release of very many equivalents of add (C -GC triple helices are a notable exception), a buffer capadty of greater than 1 mM is usually sufficient to prevent large fluctuations in pH during a melting curve. For example, we and others have observed that the adenine N1 of A -C... 

Depending upon chemical structure and the conformations that are possible, polysaccharides in solution may develop secondary structures such as helices, tertiary structures formed from junction zones or by double helix or triple helix unions and even quaternary structures from the cross linking of tertiary structures. Polysaccharides thus mimic proteins and nucleic acids, which are specific types of sugar-phosphoric acid copolymers. 

Tn orcTer to extend these conformational energy studies to the analysis of multi-stranded nucleic acid systems, it is necessary to devise a procedure to identify the arrangements of the polynucleotide backbone that can acconmodate double, triple, and higher order helix formation. As a first step to this end, a computational scheme is offered here to identify the double helical structures compatible with given base pairing schemes. 

Nucleic Acid Triple-Helices and Other Unusual Structures... 

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