Merck, F4125-100UN, Ficin from fig tree latex

General description
Extinction Coefficient: E¹% = 21.0 (280 nm)
pI: 9.0
Ficin from fig tree latex exists in multiple isoforms. The isoforms are prone to autolysis at varying temperature and tend to degrade during long term storage. It is a sulfhydryl protease with eight cysteine residues and is stabilized by three disulfide bridges.
Application
Ficin from fig tree latex has been used:
in the electron paramagnetic resonance (EPR) and steady-kinetic measurements for assessing its peroxidase functionality
for the digestion of eye tissue sections prior to immunostaining and immunofluorescence

Biochem/physiol Actions
Ficin is classified as a thiol protease. It contains a single reactive cysteine at its active site. The amino acid homology of the active site is similar to that of papain. Ficin will cleave proteins at the carboxyl side of Gly, Ser, Thr, Met, Lys, Arg, Tyr, Ala, Asn, and Val. The reported Km for the chromogenic substrate pGlu-Phe-Leu-p-nitroanilide is 0.43 mM. Ficin is inhibited by iodoacetamide, iodoacetic acid, N-ethylmaleimide, mercuric chloride, DFP (diisopropyl fluorophosphate), TLCK (Na-p-Tosyl-lysine chloromethyl ketone), and TPCK (N-Tosyl-L-phenylalanine chloromethyl ketone). Ficin can be used to generate high yielding F (ab′)₂ fragments from mouse IgG1.
Physical form
Suspension in 2.0 M NaCl and 0.03 M cysteine, pH 5.0
Preparation Note
2× Crystallized
Other Notes
One unit will produce a ΔA₂₈₀ of 1.0 per min at pH 7.0 at 37 °C when measuring TCA soluble products from casein in a final volume of 10 mL (1 cm light path).