Insight into the Mechanistic Basis of the Hysteretic-Like Kinetic Behavior of Thioredoxin-Glutathione Reductase (TGR)

Figure 11

Mechanism-based model for GSSG reductase activity of T. crassiceps TGR. Reactions 1 to 6 pertain to the ping-pong bi bi kinetic mechanism; reactions 7 to 9 correspond to the reversible inhibitory branch in which the substrate GSSG acts as noncompetitive inhibitor. Reactions 10 and 12 represent residual GSSG reductase activity of the inhibited complexes while reactions 11 and 13 correspond to reactivation of the inactive intermediaries I and I-GSSG by GSH. Reactions 1, 4, and 8 of the model correspond to those segments working under rapid equilibrium conditions.