Collagen-bound collagenase.

The presence of collagenase bound to collagen extracted and purified from several animal and human sources by a standard procedure has been confirmed by different methods. Polyacrylamide (10%) gel electrophoresis at pH 8.1 of intact or "spontaneously"degraded neutral salt soluble collagen results in the separation of two components: the upper one says at the origin and represents collagen or collagen ragments, whereas the lower protein component contains no collagen, often preserves specific collagenolytic activity, and migrates as a single band in SDS/polyacrylamide electrophoresis. With lower polyacrylamide gel concentration the electrophoretic separation of the two components is less clear. Removal of the lower protein component from collagen solutions by two different methods (TCA-ethanol purification cycles and pepsin digestion) results in concomitant loss of their "spontaneous" instability. Eluates of the lower protein component stimulate the heterologous production of a monospecific antibody capable of inhibiting the collagenolytic activity of homologous crude collagenase preparations. It is suggested that collagen-bound collagenase is not an artifact of the extraction procedure but rather a physiological reality, probably corresponding in the living animal to the enzyme closely associated with extracellular collagen fibers, revealed by immunohistochemical methods.