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Z-RNA
Z-RNA is a left-handed alternative conformation for the RNA double helix. Just like for Z-DNA Z-DNA is one of the many possible double helical structures of DNA. It is a left-handed double helical structure in which the helix winds to the left in a zigzag pattern, instead of to the right, like the more common B-DNA form. Z-DNA is thought ..., Z-RNA is favored by a sequence composed of Purine/Pyrimidine repeats and especially CG repeats. Discovery The ability of dsRNA to convert into a left-handed helix was demonstrated using NMR and circular dichroism in 1984. This conversion was shown to require high ionic strength and elevated temperatures (35 degrees). Structural characteristics Z-RNA to resemble, but not be identical, to that of Z-DNA. The structure of the complex of a Zalpha domain with Z-RNA under close to physiological salt concentrations however suggests a structure much closer to the Z-DNA conformation and points to two forms of Z-RNA (low and high salt conformations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z-DNA
Z-DNA is one of the many possible double helical structures of DNA. It is a left-handed double helical structure in which the helix winds to the left in a zigzag pattern, instead of to the right, like the more common B-DNA form. Z-DNA is thought to be one of three biologically active double-helical structures along with A-DNA and B-DNA. History Left-handed DNA was first discovered by Robert Wells and colleagues, during their studies of a repeating polymer of inosine–cytosine. They observed a "reverse" circular dichroism spectrum for such DNAs, and interpreted this (correctly) to mean that the strands wrapped around one another in a left-handed fashion. The relationship between Z-DNA and the more familiar B-DNA was indicated by the work of Pohl and Jovin, who showed that the ultraviolet circular dichroism of poly(dG-dC) was nearly inverted in 4 M sodium chloride solution. The suspicion that this was the result of a conversion from B-DNA to Z-DNA was confirmed by examini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |