Exponential Activation of Carbonic Anhydrase by Encapsulation in Dynameric Host Matrices with Chiral Discrimination.

Abstract

Herein an unexpected exponential activation of bovine carbonic anhydrase (bCA) in aqueous solutions in the presence of dynameric host matrices is reported. Successive experiments confirmed the important role of dynamic imine exchange within the dynameric host structures for direct enzyme activation. This allows for optimal encapsulation of the guest enzyme, whereas the presence of external proton-sponge amino groups is less important. Non-exchanging polymeric sec-amine congeners formed from imine reduction of dynameric structures show no obvious activation on bCA. Although the dynamers synthesized from diamino chiral-pair precursors displayed similar activation constants toward bCA, different activation delay times were observed from these two dynamers of opposite optical activity. The circular dichroism (CD) spectra demonstrate selective structural changes in the secondary structure of bCA upon dynameric encapsulation in aqueous solution. The different interaction molds observed in CD spectra for the dynamers with opposite chirality explain the longer activation time required for one of the dynamers.