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Evidence for an active‐center cysteine in the SH‐proteinase α‐clostripain through use of N ‐tosyl‐L‐lysine chloromethyl ketone
Author(s) -
Gilles A.-M.,
Keil B.
Publication year - 1984
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(84)81017-0
Subject(s) - tosyl , phenylmethylsulfonyl fluoride , chemistry , ketone , active center , phenylalanine , stereochemistry , medicinal chemistry , enzyme , organic chemistry , biochemistry , amino acid , protease
The rapid reaction of α‐clostripain with tosyl‐L‐lysine chloromethyl ketone results in a complete loss of activity and in the disappearance of one titratable SH group whereas the number of histidine residues is not affected. Tosyl‐L‐phenylalanine chloromethyl ketone and phenylmethylsulfonyl fluoride have no effect on the catalytic activity. From the molar ratio and under the assumption of 1:1 molar interaction, the fully active enzyme has a specific activity of 650–700 [twice the value proposed by Porter et al. (J. Biol. Chem. 246 (1971) 7675‐7682)]. Partial oxidation makes it experimentally impossible to attain this maximal value.