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An Activity-Based Probe for Cathepsin K Imaging with Excellent Potency and Selectivity

Publication at Faculty of Science, Faculty of Physical Education and Sport, Central Library of Charles University |
2021

Abstract

The cysteine protease cathepsin K is a target for the treatment of diseases associated with high bone turnover. Cathepsin K is mainly expressed in osteoclasts and responsible for the destruction of the proteinaceous components of the bone matrix.

We designed various fluorescent activity-based probes (ABPs) and their precursors that bind to and inactivate cathepsin K. ABP 25 exhibited extraordinary potency (k(inac)/K-i = 35,300 M(-1)s(-1)) and selectivity for human cathepsin K.

Crystal structures of cathepsin K in complex with ABP 25 and its nonfluorescent precursor 21 were determined to characterize the binding mode of this new type of acrylamide-based Michael acceptor with the particular orientation of the dibenzylamine moiety to the primed subsite region. The cyanine-5 containing probe 25 allowed for sensitive detection of cathepsin K, selective visualization in complex proteomes, and live cell imaging of a human osteosarcoma cell line, underlining its applicability in a pathophysiological environment.