Inhibitor of ProteinaseK?

[BSS032 at BANGOR.AC.UK]

Dear Netters,
I have been doing partial proteolysis with pk, now I want to stop
the reaction if possible so tha I can isolate fragments of my target protein
for N-terminal sequencing. 
So, the question is what to use as an inhibitor?
Or Any better ideas,
Thanks for the help.

Jon R Sayers (Cell and Molecular Biology), Biochemistry Dept.,
University College North Wales, Univ of Wales, Bangor, LL57 2UW.
Tel +44 248 38 23 54
Fax +44 248 370731
Email bss032 at uk.ac.bangor