Metal Ion Binding Induces Local Protein Unfolding and Destabilizes Human Carbonic Anhydrase II.

ABSTRACT: Human carbonic anhydrase II (HCA) is a robust metalloprotein and an excellent biological model system to study the thermodynamics of metal ion coordination. Apo-HCA binds one zinc ion or two copper ions. We studied these binding processes at five temperatures (15-35 °C) using isothermal titration calorimetry, yielding thermodynamic parameters corrected for pH and buffer effects. We then sought to identify binding-induced structural changes. Our data suggest that binding at the active site organizes 6-8 residues; however, copper binding near the N-terminus results in a net unfolding of 6-7 residues. This surprising destabilization was confirmed using circular dichroism and protein stability measurements. Metal binding induced unfolding may represent an important regulatory mechanism,

SUBMITTER: McConnell KD 

PROVIDER: S-EPMC8919859 | biostudies-literature | 2022 Jan

REPOSITORIES: biostudies-literature