leupeptin leupeptin leupeptin, also known as n-acetyl-l-leucyl-l-leucyl-l-argininal, is a naturally occurring protease inhibitor that can inhibit cysteine, serine and threonine peptidases. leupeptin names iupac name n-acetyl-leucyl-n--leucinamide identifiers cas number 55123-66-5 y 3d model (jsmol) interactive image chebi chebi:6426 n chemspider 65357 y echa infocard 100.212.237 pubchem cid 72429 unii j97339nr3v y comptox dashboard (epa) dtxsid1020776 inchi inchi=1s/c20h38n6o4/c1-12(2)9-16(24-14(5)28)19(30)26-17(10-13(3)4)18(29)25-15(11-27)7-6-8-23-20(21)22/h11-13,15-17h,6-10h2,1-5h3,(h,24,28)(h,25,29)(h,26,30)(h4,21,22,23)/t15-,16-,17-/m0/s1 ykey: gdbqqvlciarpgh-ulqddvlxsa-n y smiles cc(c)c(nc(c)=o)c(=o)n(cc(c)c)c(=o)n(cccnc(n)=n)c=o properties chemical formula c20h38n6o4 molar mass 426.562 g·mol−1 related compounds related alkanamides gusperimus related compounds synthalin except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references it is often used during in vitro experiments when a specific enzymatic reaction is being studied. when cells are lysed for these studies, proteases, many of which are contained within lysosomes, are released. these proteases, if freely present in the lysate, would destroy any products from the reaction being studied, and make the experiment uninterpretable. for example, leupeptin could be used in a calpain extraction to keep calpain from being hydrolyzed by specific proteases. the suggested concentration is 1-10 μm (0.5-5 μg/ml). leupeptin is an organic compound produced by actinomycetes, which inhibits serine, cysteine and threonine proteases. leupeptin inhibits serine proteinases (trypsin (ki=3.5 nm), plasmin (ki= 3.4 nm), porcine kallikrein), and cysteine proteinases (papain, cathepsin b (ki = 4.1 nm), endoproteinase lys-c). it does not inhibit α-chymotrypsin or thrombin. leupeptin is a competitive transition state inhibitor and its inhibition may be relieved by an excess of substrate. leupeptin is soluble in water (stable for 1 week at 4 °c and 1 month at −20 °c), ethanol, acetic acid and dmf. it can be given topically for middle and inner ear infections. crystal structure of leupeptin (silver) in the trypsin (green) binding pocket. hydrogen bonds are shown as yellow dotted lines. rendered from pdb 1jrs.