Bovine brain cathepsin D: inhibition by pepstatin and binding to concanavalin A.
1. Cathepsin D from bovine brain has been purified 1100-fold in 46% recovery. Three isozymes are present with pI (+/- 0.05) = 6.10, 6.30 and 6.40. 2. The isozymes are single polypeptide chains with apparent Mr = 42,000 and are similar with respect to substrate binding and cleavage; the pH-optimum is 3.5 with virtually no activity at neutral pH. 3. Pepstatin inhibits the enzyme and kinetic data are consistent with a "tight binding" mechanism. 4. The dissociation constant for the concanavalin A-enzyme complex is Kd = 19 nM at pH 5.0. 5. Under conditions where 90% of the enzyme is bound to soluble concanavalin A, full enzymatic activity is observed.
Young
P R
PR
Department of Chemistry, University of Illinois, Chicago 60680.
Karunatilake
C
C
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002402:Cathepsin D / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism; D002417:Cattle; D003208:Concanavalin A / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010436:Pepstatins / Q000494:pharmacology*
D010436:Pepstatins; D003208:Concanavalin A; C014195:Streptomyces pepsin inhibitor; D002402:Cathepsin D; C031375:pepstatin