A metalloproteinase which degrades helical regions of native collagen to small fragments. Preferred cleavage is -Gly in the sequence -Pro-Xaa-Gly-Pro-. Six forms (or 2 classes) have been isolated from clostridium histolyticum that are immunologically cross-reactive but possess different sequences and different specificities. Other variants have been isolated from bacillus cereus, Empedobacter collagenolyticum, pseudomonas marinoglutinosa, and species of vibrio and streptomyces. EC 184.108.40.206.