Chemical tools for the study of proteolytic activities associated with antigen presentation

Abstract

The synthesis of different tools to study protease activities are presented. Irreversible inhibitors of the proteasome or cathepsins were equipped with reporter groups and other functionalities to generate probes to study these proteases under different conditions. A two step labeling strategy allowed labeling of all proteasome subunits in living cells, and visualizing these activities after cell lysis. This strategy was employed further to visualize the subunit specificity of a newly developed proteasome inhibitor. An isotope coded tag was introduced in a cathepsin inhibitor in order to assess relative cathepsin activities. An crosslinking functionality or cell penetrating peptide sequence allowed active transport of cathepsin probes into cells, thereby shining a light on the uptake mechanism.