This fluorogenic probe rapidly detects cathepsin L activity with high sensitivity and selectivity. Cathepsin L is a lysosomal protease upregulated in many diseases and forms of cancer. Proteases are involved in the development and progression of cancer; inhibiting activity of cathepsin L may slow down cancer or disease progression.1 Direct measurement of the enzyme’s activity is necessary for developing pharmacologic inhibitors and assessing clinical samples for diagnostic purposes. However, available assays have various limitations. Standard fluorogenic probes have high background fluorescence that makes it difficult to ascertain true enzyme activity. These probes also can detect homologous enzymes such as cathepsin B and V by mistake, decreasing specificity to cathepsin L.
Researchers at the University of Florida have developed a fluorogenic probe that is highly selective to cathepsin L and not homologous enzymes. The probe’s structure results in less fluorescent background signal for better sensitivity to enzyme activity. Finally, activation of this fluorescent probe by cathepsin L is rapid, producing optimal results within 10 minutes.
Fluorogenic probe for rapid, selective detection of cathepsin L enzymatic activity
This fluorescent probe is chemically designed to favor the known substrate preferences of cathepsin L and not any of its homologous enzymes. Kinetic assays compared the responses of this probe and available probes to isolated cathepsin L, cathepsin B, and cathepsin V. The results indicate this newly synthesized probe has high selectivity to cathepsin L and low background fluorescence relative to available probes.