Inhibition of bovine cathepsins L and S by stefins and cystatins.
Inhibition of bovine cathepsins L and S by bovine stefin B, human stefins A and B and cystatin C was studied under pseudo-first-order conditions by continuous fluorimetric assay. All inhibitors formed very tight complexes with the enzymes (Ki < or = 29 pM). The binding was reversible (kdiss = 0.52 - 16.7 x 10(-4) s-1) and very fast (kass = 2.8 - 6.2 x 10(7) M-1 S-1). Cystatin C was the strongest inhibitor of the enzymes, but the affinity was too tight to be measured accurately by this method. Consistently weaker inhibition of cathepsin S by all the stefins is apparent due mainly to the higher dissociation rate constants.
Leonardi
A
A
Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
Turk
B
B
Turk
V
V
D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D002417:Cattle; D055313:Cystatin B; D015891:Cystatins / Q000494:pharmacology*; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D010450:Endopeptidases; D006868:Hydrolysis; D007700:Kinetics
C524994:CSTB protein, human; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D055313:Cystatin B; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C028217:cathepsin S