Abstract

The purpose of this study was to perfect a new calorimetric method for identifying and counting ionizable chemical groups on proteins. To do this, calorimetric and electrometric titrations were performed (using HCl and NaOH as titrant) on native carboxypeptidase, carbonic anhydrase and concanavalin A plus their apo and organic ligand bound derivatives. Readily identifiable endpoints were seen in the calorimetric titrations and general agreement was found between ΔH values obtained in this study and literature ΔH values of model compounds undergoing the same reaction. Imidazole groups were those most easily counted. Many assumptions had to be made, however, in concluding that imidazole groups were responsible for metal binding in these proteins. Ways of eliminating these assumptions were discussed, and the ΔH values for the denaturation of carbonic anhydrase and carboxypeptidase (which occurred at a pH of about 4 were determined).

Degree

College and Department

Physical and Mathematical Sciences; Chemistry and Biochemistry

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