What species does this chymotrypsin come from. If mammalian
chymotrypsin ever cleaved after Asp or Glu it probably never happened
again. If the manufacturer says it does fairly consistently and that info
comes from experimental observation, then the preparation is either
contaminated or is from a vastly different species. There are proteases
with mainly chymotryptic specificity that do cleave at "funny" places quite
consistently. For example, crab protease I (Grant and Eisen, Biochemistry
(1980) 19, 6089.) was shown to cleave after Phe, Tyr, Leu, and Glu and even
Lys and Arg.
Gregory A. Grant
ggrant@pharmdec.wustl.edu