J. Biol. Chem., Vol. 258, Issue 17, 10227-10232, 09, 1983
Inactivation of cathepsin B by active site-directed disulfide exchange. Application in covalent affinity chromatography
B Evans and E Shaw
The ability of cystamine, bis-N-aminoethyl disulfide, to inactivate
cathepsin B by disulfide exchange is considerably enhanced by the addition
of hydrophobic residues which apparently occupy secondary binding sites in
the extended active center of the protease. For example, a peptidyl
cystamine derivative such as symmetrical Gly-Phe- cystamine is
substrate-like and promotes the disulfide exchange by affinity labeling.
The effectiveness of this type of reagent is dependent on the peptidyl
sequence. The inactivation is more rapid with increasing pH in the narrow
range studied, pH 5-7, and is completely reversed by added thiols.
Immobilization of the peptidyl cystamine derivatives provided an effective
and rapid procedure for the covalent chromatography of cathepsin B
following ammonium sulfate fractionation of beef spleen or pork liver
homogenates, replacing the need for ion exchange chromatography. Pork liver
cathepsin B thus obtained was a mixture of single chain and double chain
forms as found by other methods.