Inactivation of GSTP1-1 by GSSG and CysSSCys.

<p>(A) GSTP1-1 (20 pmoles) incubated at 25°C with variable amounts of oxidized glutathione or oxidized cysteine in 70 µl of 0.1 M potassium phosphate buffer, pH 7.0. For comparison the same amount of GSTP1-1 was incubated with 70 µl saliva. (B) pH dependence of the inactivation by cystine (100 µM). The activity was evaluated after 5 min of incubation. Each experiment was performed in triplicate (i.e. three different spectrophotometric determinations on the same sample). Error bars represent SEM.