Syn and anti nucleosides: Difference between revisions

<applet load='Adenosine.pdb' size='300' frame='true' align='right' scene ='User:Karl_Oberholser/Sandbox_1/First_view/1'/> Observe that the adenine ring of adenosine is nearly perpendicular to the furanose ring and that a <scene name='User:Karl_Oberholser/Sandbox_1/Glycosidic_bond/1'>β glycosidic bond</scene> (colored green) connects adenine to ribofuranose.  Groups on the ribofuranose, such as the <scene name='User:Karl_Oberholser/Sandbox_1/2_hydrogen/1'>hydrogen</scene> 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 <scene name='User:Karl_Oberholser/Sandbox_1/Anti_configuration/2'>spacefill</scene> and the <scene name='User:Karl_Oberholser/Sandbox_1/Syn_configuration/1'>syn configuration</scene>, <scene name='User:Karl_Oberholser/Sandbox_1/Syn_configuration2/1'>view of adenine ring on edge</scene>, same view but in <scene name='User:Karl_Oberholser/Sandbox_1/Syn_configuration3/1'>spacefill</scene>.  With purines the anti configuration is favored, but the syn configuration can be formed and actually has a role in the formation of the [Z-DNA], a conformation of DNA double helix.