There is a very useful search box in the upper-right corner of CutDB.
http://cutdb.burnham.org/
Alexey Ersohkin describes how it can be used:
SEARCH OPTION : Examples
Protease definition : "caspase-3" "metallopeptidase-6" "furin"
Organism of protease : "Mus musculus" "Homo sapiens"
Substrate definition : "endothelin 1" or "interleukin 6"
Organism of substrate : "Mus musculus" or "Homo sapiens"
Cut-site [sequence] : "R-G" "DVED-G" "LPQK-SQHG" (“-“ shows cleavage
site location)
MEROPS code : "M10.009" "S01.251" (see
merops.sanger.ac.uk for
classification)
Disease : "AIDS" "toxic shock syndrome"
PubMed ID : "10456870" "19175361"
Acknowledgment : "HPRD" "Merops"