Firstly, a very interesting point about the alpha/beta (a/b) hydrolase fold
proteins is that they have a His-ACID-Ser triad, where examples exist for both
Asp or Glu as the acid. The first member of this family to have it's structure
determined with the His-Glu-Ser triad was a lipase from the fungus Geotrichum
candidum (Schrag et al. 1991 Nature 351, 761-764) which came out a couple of
months before the acetylcholinesterase paper (Sussman et al. 1991 Science 253,
872-879). In the Schrag et al. paper it was mentioned that the structure bore a
similar topology to the previously determined structure of the N-terminal
domain of human pancreatic lipase. The paper describing the a/b hydrolase fold
is Ollis et al. 1992 Prot. Eng. 5, 197-211. This paper also discusses the
convergent/divergent evolution issue.
Information about a/b hydrolase fold proteins can be found on the ESTHER server
http://ensam.inra.fr/cholinesterase
Kurt
-- -------------------------------------------------------------------------- Dr. Kurt Giles Department of Structural Biology | e-mail: kurt@sgjs4.weizmann.ac.il Weizmann Institute of Science | vox: +972-8-9342647 76100 Rehovot, Israel | fax: +972-8-9344159 ** http://www.weizmann.ac.il/~cskurt/home.html ** --------------------------------------------------------------------------