For the article “pH Dependence of Ion Exchange Equilibrium of Proteins,” by J. C. Bosma and J. A. Wesselingh (pp. 2399–2409, November 1998), the authors require the following erratum: In our calculations we have made a mistake with the ionic concentrations. As a result of this, we have overestimated the adsorption of acetate ions on BSA. A new evaluation of the results shows that acetate binds equally strong on BSA as chloride instead of fifty times more strongly. As a result, the ionic strengths mentioned in Figure 5 should be 20, 42, 100, and 180 mM, respectively. Those mentioned in Figure 6 should be 47, 74, 230 and 1150 mM, respectively. Those mentioned in Figure 7 should be 8, 40, 100 and 180 mM, respectively, and Figure 11 changes to the figure below. Thanks to the compensating effect of the fit parameter for adsorption of acetate on BSA, the other results are hardly affected.

In Eqs. 4 and A7, the power should be 1-|zb| instead of |zb|-1.

We apologize to the readers for the inconvenience.

Figure 1.

pH dependence of the fitted equilibrium coefficient and the net charge of BSA in acetate and tris buffers of 25 mM ionic strength.