Crude collagenase preparations contain several isoforms of two different collagenases, a sulfhydryl protease, clostripain, a trypsin-like enzyme, and an aminopeptidase. This combination of collagenolytic and proteolytic activities is effective at breaking down intercellular matrices, the essential part of tissue dissociation. One component of the complex is a hydrolytic enzyme which degrades the helical regions in native collagen preferentially at the Y-Gly bond in the sequence Pro-Y-Gly-Pro, where Y is most frequently a neutral amino acid. This cleavage yields products susceptible to further peptidase digestion. Crude collagenase is inhibited by metal chelating agents such as cysteine, EDTA or o-phenanthroline but not DFP. It is also inhibited by α2-macroglobulin, a large plasma glycoprotein. Ca2+ is required for enzyme activity. Particular enzymatic profiles of each collagenase have been correlated with the tissues from which the cells for study were obtained (or with the uses to which the cells are put) and as a result of the correlations several types of crude collagenases have been established. Crude collagenases are widely used in enzymatic primary cell isolation and tissue dissociation procedures. Most researchers employ either crude collagenase preparations such as Types 1, 2, 3, and 4 or chromatographically purified collagenase; the latter usually combined with secondary enzymes such as elastase, hyaluronidase, etc. Collagenase is ideal for researches focused in Stem Cell and Biomarker Research.