Potent and selective inactivation of cysteine proteinases with N-peptidyl-O-acyl hydroxylamines.

A series of N-peptidyl-O-acyl hydroxylamines was synthesized and tested as inactivators of cysteine proteinases. Depending on the structure of the peptidyl residue of the inhibitors, rapid and complete irreversible inactivation of the lysosomal cathepsins, B, L and S, may be achieved. The most effective inhibitors display second-order rate constants of the inactivation in the range 10(5)-10(6) M-1.s-1. By contrast, the activity of the aminoendopeptidase cathepsin H is only negligibly affected by the N-terminal-protected peptidyl inhibitors.