FIG. 3.

Participation of Pz peptidases A and B in collagen degradation. The reaction mixture, which contained 10 mg collagen (type I, bovine tendon), 1.2 μg purified collagenolytic protease from strain MO-1 (32), and purified Pz peptidase A (9.2 μg) or Pz peptidase B (30 μg) in 5 ml of a 50 mM HEPES buffer (pH 7.6 for Pz peptidase A and pH 8.4 for Pz peptidase B), was incubated with shaking at 60°C. An aliquot (300 μl) was extracted every 10 min and mixed with 0.5 M EDTA (6 μl) to stop the reaction. The increase in the number of N-terminal residues by degradation was measured following the ninhydrin method, which was described previously (12, 32). Symbols: •, Pz peptidase A, Pz peptidase B, and collagenolytic protease; ▵, Pz peptidase A and collagenolytic protease; ○, Pz peptidase B and collagenolytic protease; ◊, collagenolytic protease only; □ Pz peptidase A only; ▿, Pz peptidase B only.