Role of the single cysteine residue, Cys 3, of human and bovine cystatin B (stefin B) in the inhibition of cysteine proteinases.

ABSTRACT: Cystatin B is unique among cysteine proteinase inhibitors of the cystatin superfamily in having a free Cys in the N-terminal segment of the proteinase binding region. The importance of this residue for inhibition of target proteinases was assessed by studies of the affinity and kinetics of interaction of human and bovine wild-type cystatin B and the Cys 3-to-Ser mutants of the inhibitors with papain and cathepsins L, H, and B. The wild-type forms from the two species had about the same affinity for each proteinase, binding tightly to papain and cathepsin L and more weakly to cathepsins H and B. In general, these affinities were appreciably higher than those reported earlier, perhaps because of irreversible oxidation of Cys 3 in previous work. The Cys-to-Ser mutation resulted in weaker bind

SUBMITTER: Pol E 

PROVIDER: S-EPMC2253190 | biostudies-literature | 2001 Sep

REPOSITORIES: biostudies-literature