title: Inhibition of chicken calpain II by proteins of the cystatin superfamily and alpha 2-macroglobulin.
abstract: Inhibition of chicken calpain II by proteins of the cystatin superfamily and alpha 2-macroglobulin was investigated. Human liver cystatins A and B, human cystatin C, chicken cystatin and rat T-kininogen were found not to be inhibitory. Inhibition was, however, observed for bovine and rat kininogens, with Ki (inhibition constant) values of 0.8 nM and 30 nM respectively. alpha 2-Macroglobulin inhibits calpain with an initial rate constant of the order of 3 X 10(4) M-1.S-1. Calpain complexed with alpha 2-macroglobulin showed only limited reactivity towards azocasein, but reacted readily with the peptide substrate Suc-Leu-Tyr-4-methyl-7-coumarylamide and with L-3-carboxy-trans-2,3-epoxypropionyl-leucylamido-(4-guanidin o)butane (E-64). The calpain in the complexes was at least partially protected from loss of activity due to autolysis. The calpain-alpha 2-macroglobulin complexes contained both the calpain subunits.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002154:Calpain / Q000037:antagonists & inhibitors*; D002645:Chickens; D002850:Chromatography, Gel; D003374:Coumarins / Q000378:metabolism; D055313:Cystatin B; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D007704:Kininogens / Q000494:pharmacology*; D046911:Macromolecular Substances; D011480:Protease Inhibitors / Q000494:pharmacology*; D011506:Proteins / Q000494:pharmacology*; D000511:alpha-Macroglobulins / Q000494:pharmacology*
chemical_list: C525030:CST3 protein, human; C524994:CSTB protein, human; D003374:Coumarins; C525032:Cst3 protein, rat; D055316:Cystatin C; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D004151:Dipeptides; D007704:Kininogens; D046911:Macromolecular Substances; D011480:Protease Inhibitors; D011506:Proteins; D000511:alpha-Macroglobulins; D055313:Cystatin B; C054777:succinyl-leucyl-tyrosyl-4-methyl-7-coumarylamide; D002154:Calpain