Strategies for phosphatase inhibition and models of biomimetic catalysis.

摘要

Enzyme inhibition is a common strategy used to study activity. Effective inhibitors must display specificity and potency to the desired enzyme target. These inhibitors are chemical tools to address questions concerning biological catalysis. In particular, this thesis details two inhibition strategies to study phosphatases, a class of enzymes that catalyze the hydrolysis of phosphate esters. Reversible phosphorylation is now recognized as the pre-eminent mode of cellular communication in biological systems. Understanding the details of enzymecatalyzed phosphate ester hydrolysis may extend our general understanding of how enzymes catalyze chemical reactions.; Many phosphatase inhibitors incorporate functionality to mimic the charge and geometry of the natural phosphorylated substrate. The most direct substitution is replacement of the phosphate moiety by a nonhydrolyzable phosphonate. These derivatives and their analogues are typically poor inhibitors of metallophosphatases. Phosphonic acids bearing pendant ligands are shown to be effective inhibitors of metallophosphatases. In conjunction with inhibitor structure-activity studies, X-ray structure analyses were used to illustrate the various binding modes of two inhibitors to alkaline phosphatase.; Protein-protein interactions govern many biological processes. This thesis describes the synthesis of a site-specific protein modification tool. This tool can be used to probe the importance of these interactions on protein tyrosine phosphatase (PTPase) activity and/or inhibition. These molecules are designed to easily incorporate a PTPase-specific inhibitor motif into a folded protein framework. This displayed inhibitor can now “borrow” the surrounding surface area to increase recognition by PTPases. The described syntheses provide a combinatorial approach to efficiently adjust the specific protein-inhibitor conjugate.; There is a long history of developing artificial catalysts based on enzymatic reaction mechanisms. Many of these efforts have been largely unsuccessful. The catalytic machinery utilized by sulfatases was attached to a cyclodextrin scaffold. This biomimetic model was examined as a catalyst of ester hydrolysis. Additionally, simple aldehyde hydrates were assayed hydrolytic catalysts. Collectively, these chemical methods are designed to further our understanding of enzymatic catalysis.