Extinction Coefficient: E^1% = 21.0 (280 nm)
pI: 9.0

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 K_m 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.

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).

The enzyme is soluble in 1 M potassium phosphate buffer, pH 7.0 (0.25 mg/ml), yielding a clear solution.