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Clostripain: Characterization of the active site
Author(s) -
Kembhavi Ashu A.,
Buttle David J.,
Rauber Peter,
Barrett Alan J.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80607-5
Subject(s) - iodoacetamide , chemistry , hydroxylamine , active site , histidine , leupeptin , cysteine , biochemistry , enzyme , protease
In view of the probability that clostripain (EC 3,4,22.8) is fundamentally different in structure from other known cysteine endopeptidases. It was of interest to examine the characteristics of the active site Z‐Pho‐Lys‐CH 2 S(CH 3 ) 2 irreversibly and rapidly inactivated clostripain, and leupeptin was found to be the most potent reversible inhibitor yet reported for the enzyme. Clostripain was inhibited weakly by some protein inhibitors of serine endopeptidases, and required Ca + for stability and activity. Mg 2+ and Sr 2+ were ineffective. Rapid inactivation by diethylpyrocarbonate, reversed by hydroxylamine, indicated that histidine is essential for catalytic activity. Clostripain was more rapidly inactivated by iodoacetamide than by iodoacetate, with unique pH‐dependences or reaction.