Sugar ring pucker: Difference between revisions

==Relieving ring strain==

For a 5-membered ring with perfectly tetrahedral geometry of each atom in the ring, there is some strain if the ring were planar (355 degree rotation around the ring instead of 360). To relieve the strain, one or two atoms move out of the plane. The conformation with one atom out of the plane is called envelope (endo or exo depending on whether the atom is above or below the plane). The conformation with two consecutive atoms out of the plane, one above and one below, is called twist. More than two atoms are never out of plane because the remaining three atoms always define a plane.

==Describing conformations with a pseudorotation angle==