Enterokinase Specificity

Tim Green green at salk.edu
Thu May 29 20:06:07 EST 1997


We seem to have a specificity problem with enterokinase, and wonder if
anyone has any ideas.

We are working with a soluble protein produced in High5 insect cells.  The
N-terminus carries an epitope which includes an enterokinase recognition
site (DDDDK).  There are (unsurprisingly), no other such sequences in the
polypeptide (~40kDa).  When we digest with the enzyme for 5 hours at 4°C,
the protein is cleaved into two fragments at a site clearly different from
the expected N-terminal one.

suggestions?  The enterokinase was purchased from Strategene (supposedly
sequencing grade).

Tim Green



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