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Back to Main Index . . . last updated 12th.April'95
To best appreciate the content of this chapter you need to INTERACTIVELY EXAMINE a number of protein structures. If you haven't done so already, we STRONGLY URGE you to install the FREE molecular viewer software, RasMol and configure it to be automatically invoked by chemical/MIME. See our Technology Page to find out how.

Since the two well-defined secondary structural units of helices and sheets are abundant in proteins, families of protein structures have been classified by a system based upon the alpha-helix and beta sheet and their general topological properties. Each different topology may be considered as a fold. Current thinking suggests that there are a limited number of folds found in naturally occuring proteins.:-

You are also advised to study these databases of structural classification

Remember, if you know the 4-letter PDB code, you MAY be able to access the structure using a URL of the form http://www.cryst.bbk.ac.uk/PDB/pdbcode.pdb

If you have MAGE installed and configured for Chemical MIME, you can view the Branden and Tooze, Protein Science and Protein Tourist Kinemages, some of which are relevant to this material. Again, refer to the Technology Page if necessary. There are some links to appropriate Kinemages within this chapter.


We wish to thank the following for material incorporated into this chapter

John Overington, Birkbeck & Pfizer
Gail Schumann & Jane Richardson
Alexey G. Murzin, Steven E. Brenner, Tim J.P. Hubbard, and Cyrus Chothia for SCOP
C.A. Orengo, A.D. Michie, J.M. Thornton, & W.R. Taylor for CATH
Manuel Peitsch, GLAXO, Geneva

John Walshaw & Alan Mills, Birkbeck College, Apr'95