Figure 2.

Reactivity of protein cysteines toward disulfides and thiol reagents normalized to that of GSH and free Cys. Second-order kinetic constants of the rRNase toward GSSG (red bars) normalized to the constant calculated for an unperturbed protein cysteine (0.2 M⁻¹ s⁻¹) (see Materials and Methods) represent the “enhanced reactivity”. All other bars represent the second-order kinetic constants of the rRNase in its reactions with other disulfides and thiol reagents normalized to the constants for free GSH. Error bars represent the propagation of uncertainties for the quotients [20] (see Materials and Methods).