Four Levels Of Protein Structure?

Question

Does anyone have a website that illustartes the four levels of protein structures? I need it for a project along with the description.

Answer 1

This is from my bioinformatics class days, might be over shooting the goal:

http://us.expasy.org/tools/#tertiary

has tools for primary, secondary and tertiary, quatinary is just when two tertiary join together, like in hemeglobin to hold an iron molecule.

Answer 2

here is a picture and description of the 4 levels
http://www.umass.edu/molvis/workshop/prot1234.htm