Site specific proteases and chimeric proteins

[Eric R. Hugo]

Dear netters,
     I am about to construct a fusion protein that I would like to
specifically cleave.  I've heard of several aa sequence specific
proteases such as Factor Xa, etc.  Has anyone had any experience
with proteases of this nature (both good and bad)?  Can anyone
recommend first a good overall reference and possible sources for these
enzymes.  Please email responses I'll post a summary if requested.
     Thanks for your time.                   Eric ;-)
-- 
  Eric R. Hugo, Postdoctoral Research Associate |eric at bcserv.wustl.edu
  Dept. of Biochemistry and Molecular Biophysics|                
  Washington University School of Medicine      |               
  Box 8231, St. Louis, MO 63110_________________| (314) 362-3342