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Syn and Anti Configurations of Nucleosides and Nucleotides
Detailed description of nucleosides and nucleotides.
Purine Nucleosides
Observe that the adenine ring of adenosine is nearly perpendicular to the furanose ring and that a (colored green) connects adenine to ribofuranose. Groups on the ribofuranose, such as the on the 2' carbon sterically hinder the rotation of the adenine about the glycosidic bond. This lack of ability to rotate results in two possible configurations. The anti configuration, which you have been viewing, but now in and the , , same view but in . With purines the anti configuration is favored, but the syn configuration can be assumed and actually has a role in the formation of the
Z-DNA, a conformation of DNA double helix.
Pyrimidine Nucleosides
of uridine in the anti conformation. of cytidine in the syn conformation.
