Re: [ccp4bb] structure <-> function

[Roger Rowlett]

How about five (!) convergently evolved proteins? The carbonic anhydrases are a well-known family of proteins which (to date) have 5 independently convergently evolved forms: alpha, beta, gamma, delta, and zeta. (Epsilon got folded into beta after crystallography revealed it to be a beta-form.) Four of those have X-ray crystallographic structures (alpha, beta, gamma, and zeta). These proteins have a range of folds, including a unique one for beta, but all have active sites that can be very closely mapped onto each other. All have evolved to be metalloenzymes (zinc, iron, and cadmium are represented to date in in vivo foms, all can function with zinc) with a metal-hydroxide mechanism with some rather specific hydrogen bond network requirements, and a rate-limiting proton transfer step. At least for this protein, the question of convergent evolution is multiple choice (one best answer), not essay question format. Cheers. Justin Lecher wrote: Hello everxone, I am looking for an example of two proteins where the primary sequence does not show any significant similarities, but which have the same function due their structure? I want to use it to demonstrate that function could not always deduced from sequence alignments, but from structure alignments. Does anyone could give me some good examples? Thanks Justin -- Roger S. Rowlett Professor Department of Chemistry Colgate University 13 Oak Drive Hamilton, NY 13346 tel: (315)-228-7245 ofc: (315)-228-7395 fax: (315)-228-7935 email: rrowl...@mail.colgate.edu