Cellular protease inhibitors are molecules that interfere with the activity of proteases, which are the enzymes responsible for catalysing the breakdown of proteins into smaller peptides or amino acids. Protease inhibitors can be natural or synthetic compounds that target specific proteases or inhibit protease activity more broadly. Their specific mechanisms of action vary depending on the inhibitor and the targeted protease. Some protease inhibitors utilize competitive inhibition by resembling the substrate molecules that proteases normally cleave. These inhibitors act by binding to the active site of the protease and compete for substrate binding. An example of a serine protease inhibitor that utilizes competitive inhibition is antithrombin III, which inhibits the blood clotting protease thrombin. Instead of binding to the active site, some inhibitors bind to a different site on the protease molecule called an allosteric site. This mode of inhibition, although less common, induces a conformational change in the protease, altering its active site's shape or accessibility. As a result, the protease cannot effectively bind its substrate and carry out the cleavage reaction. One example is calpastatin, an endogenous inhibitor of calpains, a family of calcium-dependent cysteine proteases involved cytoskeletal remodelling. Calpastatin does not directly bind to the active site of calpains but rather binds to an allosteric site on the enzyme, leading to conformational changes that inhibit its proteolytic activity. Certain other protease inhibitors form covalent bonds with specific amino acid residues within the protease active site, thereby inhibiting the protease's catalytic activity. These irreversible inhibitors are generally small molecules and include proteasome inhibitors, such as bortezomib and carfilzomib. These inhibitors bind irreversibly to the active site of the proteasome by forming a covalent bond with the catalytic threonine residue in the proteasome's active site, inhibiting proteosome activity. Other covalent inhibitors include the organophosphates (e.g., sarin and soman) and carbamates (e.g., physostigmine and neostigmine) that covalently bind to the serine residue in the active site of acetylcholinesterase, an enzyme involved in the breakdown of the neurotransmitter acetylcholine, inhibiting its activity. Inhibitors can also prevent the activation of zymogens, proteases synthesized as inactive precursors, by blocking the proteases responsible for their activation. Examples of this mode of inhibition include: 1) aprotinin, a broad-spectrum serine protease inhibitor of various zymogens, including plasminogen and trypsinogen; 2) alpha-1-antitrypsin, a serine protease inhibitor that primarily targets elastase but can also inhibit other zymogens, such as trypsinogen and chymotrypsinogen; 3) alpha-2-macroglobulin, that can inhibit the activation of plasminogen and trypsinogen; 4) serpins (Serine Protease Inhibitors), a family of protease inhibitors that include antithrombin, which inhibits the activation of thrombin, and plasminogen activator inhibitor-1 (PAI-1), which inhibits the activation of plasminogen. Two final types of protease inhibitors important in cell biology are the cysteine protease inhibitors and metalloprotease inhibitors. Cysteine protease inhibitors such as cystatins or the synthetic inhibitor E-64 irreversibly inhibit cysteine proteases by reacting with the active site cysteine residue, whilst metalloprotease inhibitors target metalloproteases, which require a metal ion cofactor for their activity and include TIMPs (Tissue Inhibitors of Metalloproteinases), endogenous inhibitors that regulate the activity of matrix metalloproteinases (MMPs), involved in extracellular matrix remodelling. We provide a large product range of research reagents for studying protease inhibitors, including TIMP2 antibodies, TIMP1 antibodies, alpha 2 Macroglobulin antibodies, Tissue Factor Pathway Inhibitor ELISA Kits, and TIMP1 ELISA Kits. Explore our full protease inhibitors product range below and discover more, for less. Alternatively, you can explore our Serine Protease Inhibitors and Metalloprotease Inhibitors product ranges.