Zymography is a powerful technique for the assay of different hydrolases that act upon any biological macromolecule. In particular, zymography is used to assay the activities of serine proteases, e.g., matrix metalloproteinases (MMPs), and reverse zymography is used for tissue inhibitors of metalloproteinases (TIMPs) in multifarious experimental samples. Zymography is a method of electrophoretic separation of proteases under non-reducing conditions in a polyacrylamide gel containing substrate. The resolved proteins are renatured by exchange of the anionic detergent with a nonionic one, and the gel is incubated in a specific buffer for the specific proteases. After staining the gel by Coomassie blue staining solution, the proteolytic activities are visualized as clear colorless bands against a dark background. In contrast, reverse zymography is a parallel technique to detect protease inhibitors. In addition to substrate gelatin, proteases (i.e., MMPs) are also incorporated in proper ratio into the polyacrylamide gel. After electrophoresis, during the developing step, the MMPs specifically digest the substrate in regions where TIMPs are absent. Thus, inhibitors/TIMP is represented as dark zones of inhibition against a transparent background after staining. In this chapter, common troubleshoots during sample preparation, running zymography, and data interpretation are discussed. Notes are specified to enhance the sensitivity of the methods. In conclusion, zymography could be crucial for enzyme assay at the nanogram level and for the improvement of new investigative techniques for diseases such as endometriosis, rheumatoid arthritis, osteoarthritis, tumor invasion, and inflammation.
Keywords: Casein; Electrophoresis; Gelatin; MMPs; Protease-activity; Reverse zymography; Substrate-gel; TIMPs; Zymography.
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