Collagenases are zinc endopeptidases that digest nearly all collagen fibers in their insoluble triple-helical form. Sigma′s enzymes from Clostridium histolyticum digest both the insoluble fibrous collagen in the extracellular matrix as well as the soluble fragments that result when the triple helix is cleaved. Since collagens are the major protein component of extracellular matrix, collagenases are a useful tool in preparing cells for culture. Our collagenase products differ in their suitability for digesting tissue from different organs. Easily inhibited by both EDTA and EGTA, tissue digestion with collagenase can be carefully controlled to release cells unharmed from their surroundings.