Influence of the Zn(II) cofactor on the refolding of bovine carbonic anhydrase after denaturation with sodium dodecyl sulfate

Abstract

This paper uses capillary electrophoresis to follow a globular metalloprotein--bovine carbonic anhydrase II (BCA, EC 4.2.1.1)--on unfolding upon treatment with sodium dodecyl sulfate (SDS) and refolding upon removal of SDS, both in the presence and the absence of its Zn(II) cofactor. This research demonstrates that the Zn(II) cofactor is not required for refolding into a nativelike conformation, does not remain associated with the unfolded protein, and does not significantly change the rate of refolding. The presence of the Zn(II) cofactor, however, does increase the total amount of recovered protein by a factor of 2. Capillary electrophoresis could distinguish between native and denatured protein, based on the difference in electrophoretic mobility between the native protein and the aggregate of denatured protein and SDS. In addition, the active site was probed by observing binding of BCA to a charged arylsulfonamide using affinity capillary electrophoresis. These studies provide a foundation for future physical-organic studies using BCA as a model to examine interactions between proteins and SDS.