Leupeptin, or N-acetyl-L-leucyl-L-leucyl-L-argininal, is a naturally occurring tripeptide and a reversible Inhibitor of serine and cysteine proteases. Competitively inhibits calpain, cathepsin B, kallikrein, papain, plasmin, and trypsin, but is little or non-inhibiting for pepsin, cathepsin A and D, chymotrypsin, and thrombin.
Leupeptin forms in the active site of serine proteases a covalent hemiacetal adduct between the aldehyde group of leupeptin and the hydroxyl group of a serine residue in the enzyme active site. Inhibition of cysteine proteases is achieved by forming a comparable bond between the electrophilic (aldehyde) carbon of leupeptin with the sulfur atom of a cysteine residue in the enzyme active site.
Due to its aldehyde groups, leupeptin may interfere with protein detection assays (e.g. Bradford).
Stock solution: 5 mg/ml (10 mM) in H2O, ethanol, acetic acid and DMF (stabile at +4 °C for approx. 7 days and at -20 °C for approx. 6 months)
Working concentration: 1 - 100 µM (stabile only for few hours) Acetyl-L-leucyl-L-leucyl-L-argininal
C20H38N6O4·1/2H2SO4 Mr 475.6 CAS No. 103476-89-7 Assay (HPLC) (sum of tautomeric isomers): min. 96.5 % |
