Proteasomes are very large protein complexes inside all eukaryotes and archaea, and in some bacteria. In eukaryotes, they are located in the nucleus and the cytoplasm. The main function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Enzymes that carry out such reactions are called proteases. Proteasomes are part of a major mechanism by which cells regulate the concentration of particular proteins and degrade misfolded proteins. The degradation process yields peptides of about seven to eight amino acids long, which can then be further degraded into amino acids and used in synthesizing new proteins. Proteins are tagged for degradation with a small protein called ubiquitin. The tagging reaction is catalyzed by enzymes called ubiquitin ligases. Once a protein is tagged with a single ubiquitin molecule, this is a signal to other ligases to attach additional ubiquitin molecules. The result is a polyubiquitin chain that is bound by the proteasome, allowing it to degrade the tagged protein.
MG-132 is a potent, reversible, and cell-permeable 20S proteasome inhibitor which inhibits proteasomal chymotrypsin-like peptidase activity with an IC50 of 24.2 nM.
Tripterin (Celastrol) is a proteasome inhibitor which potently and preferentially inhibits the chymotrypsin-like activity of a purified 20S proteasome with IC50 of 2.5 μM.
MDL-28170 (Calpain Inhibitor III) is a potent, selective and membrane-permeable cysteine protease inhibitor of calpain that rapidly penetrates the blood-brain barrier following systemic administration. MDL-28170 also block γ-secretase.
Pepstatin Ammonium is a specific aspartic protease inhibitor produced by actinomycetes, with IC50s of 4.5 nM, 6.2 nM, 150 nM, 290 nM, 520 nM and 260 nM for hemoglobin-pepsin, hemoglobin-proctase, casein-pepsin, casein-proctase, casein-acid protease and hemoglobin-acid protease, respectively. Pepstatin Ammonium also inhibits HIV protease.
LMP7-IN-1 is an inhibitor of immunoproteasome (LMP7), may used in the research of inflammatory and autoimmune diseases, neurodegenerative diseases, proliferative diseases and cancer.
Pepstatin is a specific aspartic protease inhibitor produced by actinomycetes, with IC50s of 4.5 nM, 6.2 nM, 150 nM, 290 nM, 520 nM and 260 nM for hemoglobin-pepsin, hemoglobin-proctase, casein-pepsin, casein-proctase, casein-acid protease and hemoglobin-acid protease, respectively. Pepstatin Ammonium also inhibits HIV protease.
Pepstatin Trifluoroacetate is a specific aspartic protease inhibitor produced by actinomycetes, with IC50s of 4.5 nM, 6.2 nM, 150 nM, 290 nM, 520 nM and 260 nM for hemoglobin-pepsin, hemoglobin-proctase, casein-pepsin, casein-proctase, casein-acid protease and hemoglobin-acid protease, respectively. Pepstatin Ammonium also inhibits HIV protease.
Ixazomib (MLN2238) is a selective, potent, and reversible proteasome inhibitor, which inhibits the chymotrypsin-like proteolytic (β5) site of the 20S proteasome with an IC50 of 3.4 nM (Ki of 0.93 nM).
Ixazomib citrate (MLN9708) is a reversible inhibitor of the chymotrypsin-like proteolytic β5 site of the 20S proteasome with an IC50 of 3.4 nM and a Ki of 0.93 nM.
MG-101 is a potent inhibitor of cysteine proteases which inhibits calpain I, calpain II, cathepsin B and cathepsin L with Kis of 190, 220, 150 and 500 pM, respectively.
Delanzomib(CEP-18770) is a novel orally-active inhibitor of the chymotrypsin-like activity of the proteasome that down-modulates the nuclear factor-kappaB (NF-kappaB) activity.
