Leland Stanford Junior University

Galia Blum

Matthew S Bogyo

Sanjiv Sam Gambhir

Zhen Cheng

Georges Von Degenfeld

Alicia Berger

Methods and materials for the imaging of cells containing active proteases such as cathepsin are disclosed. The present materials include activity based probes that bind to an enzyme and are subsequently cleaved. Cleavage results in a fluorescent signal due to removal of a quenching group which, when present on the probe causes altered or no fluorescence. The probes employ an acyloxymethyl ketone reactive group, one or more amino acids for determining specificity, a fluorophore and a quencher. The probes are cell permeable and may use, for example, a QSY7 (diarylyrhodamine) quencher and a BODIPY (bora-diaza-indecene) dye.

Imaging of protease activity in live cells using activity based probes

Activity-based probes, which are specific for certain active cysteine proteases (caspase, cathepsin and legumain) and carry radioactive labels, are disclosed. The present probes comprise an acyloxymethyketone (AOMK) 'warhead' that binds only to active enzyme. The probes further comprise peptide-like structure that targets the probe to a specific cysteine protease or protease family, and a radiolabel on the probe, which is bound to the targeted enzyme. It has been found that the present probes are stable in vivo and give specific target images distinguishable over background. The preferred probes are labeled with a positron-emitting agent such asCu,I (SPECT) andTc (PET). The probes show in vivo half-life and stability well suited for imaging.

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Palo Alto, CA, United States of America

Galia Blum