| Abstract
| - A series of charge ladders of bovine carbonic anhydraseII were synthesized and the relative abundances of therungs analyzed by capillary electrophoresis as a functionof the quantity of acylating agent used. A simulation thatmodels the kinetics of formation of the members of thecharge ladders is described. The observed rate constantsdecreased as the extent of acylation increased. These rateconstants correlated adequately with theoretical rateconstants calculated using Debye−Hückel theory. Thedata are compatible with, but do not demand, a modelfor the formation of this charge ladder in which allunacetylated amino groups in each rung have indistinguishable reactivity and in which the reactivity of theamines in each rung decreases as the net charge on theprotein increases; in this model, decreased reactivity isdue to increased extent of protonation. This agreementbetween experiment and model suggests that the chargeshielding that results from an ionic strength of 130 mMis not sufficient to suppress the influence of the increasingly negative charge of the protein with acetylation on theextent of protonation of Lys ε-NH2 groups.
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