Characterization of caspase‐2 inhibitors based on specific sites of caspase‐2‐mediated proteolysis

Abstract

Since the discovery of the caspase‐2 (Casp2)‐mediated ∆tau314 cleavage product and its associated impact on tauopathies such as Alzheimer's disease, the design of selective Casp2 inhibitors has become a focus in medicinal chemistry research. In the search for new lead structures with respect to Casp2 selectivity and drug‐likeness, we have taken an approach by looking more closely at the specific sites of Casp2‐mediated proteolysis. Using seven selected protein cleavage sequences, we synthesized a peptide series of 53 novel molecules and studied them using in vitro pharmacology, molecular modeling, and crystallography. Regarding Casp2 selectivity, AcITV(Dab)D‐CHO (23) and AcITV(Dap)D‐CHO (26) demonstrated the best selectivity (1–6‐fold), although these trends were only moderate. However, some analogous tetrapeptides, most notably AcDKVD‐CHO (45), showed significantly increased Casp3 selectivities (>100‐fold). Tetra‐ and tripeptides display decreased or no Casp2 affinity, supporting the assumption that a motif of five amino acids is required for efficient Casp2 inhibition. Overall, the results provide a reasonable basis for the development of both selective Casp2 and Casp3 inhibitors.

Conditional Cell-Penetrating Peptide Exposure as Selective Nanoparticle Uptake Signal

“…The corresponding results are provided in the Supporting Information ( Figures S1–S20 ). The synthesis was performed using a standard Fmoc strategy following the procedure of Bresinsky et al 30 The 2-chlorotrityl-resin (300 mg, 1 equiv) was weighted into a fritted 25 mL syringe. 15 mL of dichloromethane (DCM) was drawn up to swell the resin at room temperature (RT) for 30 min.…”