Thanks all for the suggestions! I made some slides but they are not really what I hoped for... Anyway, I can provide them for anyone on request. Now I have another question - What is the original reference for the 'well known fact' that protein structure is more conserved than sequence? It was pointed out by Max Perutz when the first protein structures were solved in parrallel with John Kendrew (heamaglobin / myoglobin from horse / whale although I forget which from which). They didn't see sequence identity, but found structural identity (by conincidence?). Also the protein was all alpha, just after Linus Pauling predicted that would be a stable form of protein. I was thinking that the original RMSD / sequence identity relationship by Chothiea and Lesk, but that dosen't really show the fact that the structure is conserved as sequence diverges. Or does it? Is there a reprint of the latter article? Cheers, Dan.