Dipeptidyl peptidase IV from porcine skeletal muscle: purification and biochemical properties

Dipeptidyl peptidase IV (EC 3. 4. 14. 5) from porcine skeletal muscle has been purified to homogeneity by selective protein fractionation with ammonium sulfate and HPLC separations with strong anion-exchange chromatography. Pure DPP IV showed a single band with Mr about 70 kDa by SDS-PAGE and optimum activity at pH 8.0 and 45°C. Substrates best hydrolyzed were those containing a proline residue in the penultimate position at the N-terminal, but it was also possible to hydrolyze (in lower amounts), X-Ala- synthetic and peptide substrates. The presence of diprotin A, puromycin, Co2+ and Fe2+ considerably inhibited DPP IV activity. A contribution of DPP IV action to the total proteolytic activity occurring in postmortem muscle during meat storage and ripening of meat products is feasible and could contribute to flavor generation in those products.