Papaya proteinase OMEGA (ppOMEGA) has been purified from dried latex b
oth by immunoaffinity and traditional methods. Kinetic analysis reveal
ed that (1), the ppOMEGA-catalysed hydrolysis of N-benzoyl-L-arginine
p-nitroanilide (BApNA) has a lower specificity (k(cat)/K(m)) than the
same reaction catalysed by papain; (2), the ppOMEGA-catalysed hydrolys
is of a tripeptide substrate having phenylalanine at the second positi
on (S2-site) showed a more similar specificity to that catalysed by pa
pain; (3), the significant difference between the two enzymes is that
steady state kinetics with both L-BApNA and a tripeptide enables the i
dentification in ppOMEGA of other ionizations affecting binding. The a
ctive sites of papain and ppOMEGA can therefore be distinguished by pH
-dependence of k(cat)/K(m).