A proform of high molecular weight type IV collagenase was isolated and purified 1230-fold from human metastatic carcinoma tissue. Like matrix metalloproteinases (MMPs), the enzyme was activated by trypsin and degraded type IV collagen and gelatin at a neutral pH, the activity was inhibited by EDTA and o-phenanthroline. However, the molecular weight was much higher than MMPs which degraded type IV collagen, gelatinase A (MMP-2; 72 kDa gelatinase/type IV collagenase) (EC 3.4.24.24), gelatinase B (MMP-9; 92 kDa gelatinase/type IV collagenase) (EC 3.4.24.35), stromelysin-1 (MMP-3; 57 kDa) (EC 3.4.24.17) and stromelysin-2 (MMP-10; 57 kDa) (EC 3.4.24.22). The other significant difference from MMPs was that the enzyme was not activated by 4-aminophenylmercuric acetate nor inhibited by TIMP. Taking together these results, this high molecular weight type IV collagenase might be a newly found enzyme different from MMPs or might have the same configuration as MMPs already reported.
