Comparative behaviour of calpain and cathepsin B toward peptidyl acyloxymethyl ketones, sulphonium methyl ketones and other potential inhibitors of cysteine proteinases.
Peptidyl acyloxymethyl ketones, previously established as potent inactivators of the lysosomal cysteine proteinase cathepsin B, were evaluated against smooth-muscle calpain, a member of the family of Ca(2+)-dependent cysteine proteinases. Only modest rates of time-dependent inhibition could be achieved, even with peptidyl affinity groups optimized for calpain and linked to a carboxylate leaving group of very low pKa [2,6-(CF3)2PhCOO-, pKa 0.58]. Selective inactivation of cathespin B versus calpain was consistently observed with this type of inhibitor. Examination of other potential inhibitors revealed a rank order of potency against calpain to be: peptidyl sulphonium methyl ketones > fluoromethyl ketones, diazomethyl ketones >> acyloxymethyl ketones, an order which differs sharply from that found for cathespin B.
Pliura
D H
DH
Syntex Research, Mississauga, Ontario, Canada.
Bonaventura
B J
BJ
Smith
R A
RA
Coles
P J
PJ
Krantz
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002154:Calpain / Q000037:antagonists & inhibitors*; D002401:Cathepsin B / Q000037:antagonists & inhibitors*; D002645:Chickens; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D007659:Ketones / Q000494:pharmacology*; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013452:Sulfonium Compounds / Q000494:pharmacology*
D015853:Cysteine Proteinase Inhibitors; D007659:Ketones; D010455:Peptides; D013452:Sulfonium Compounds; D002154:Calpain; D002401:Cathepsin B