Here are PDB files illustrating Psi = +90 and Psi = -90 degrees. These are similar to the peptides I used to make the overhead shown in class. The top pair of images are linked to PDB files. Note that Rasmol makes weird cyclic arrnagements when there is steric hindrance.

Psi = -90 degrees	Psi = +90 degrees
This is linked to a PDB file:	This is linked to a PDB file:
These are the similar images from class: