Imaging of extracellular cathepsin S activity by a selective near infrared fluorescence substrate-based probe.

Imaging of extracellular cathepsin S activity by a selective near infrared fluorescence substrate-based probe.
Biochimie. 2019 Mar 23;:
Authors: Wartenberg M, Saidi A, Galibert M, Joulin-Giet A, Burlaud-Gaillard J, Lecaille F, Scott CJ, Aucagne V, Delmas AF, Lalmanach G
Abstract
We designed a near-infrared fluorescent substrate-based probe (SBP), termed MG101, for monitoring extracellular cathepsin S (CatS) activity. We conceived a fused peptide hairpin loop-structure, combining a CatS recognition domain, an electrostatic zipper (with complementary charges of a polyanionic (D-Glu)5 segment and a polycationic (D-Arg)5 motif, as well as a N- and C- terminal Förster resonance energy transfer pair (donor: AlexaFluor680; quencher: BHQ3) to facilitate activity-dependent imaging. MG101 showed excellent stability since no fluorescence release corresponding to a self-dequenching was observed in the presence of either 2 M NaCl or after incubation at a broad range of pH (2.2-8.2). Cathepsins B, D, G, H, and K, neutrophil elastase and proteinase 3 did not cleave MG101, while CatS, and to a lesser extent CatL, hydrolysed MG101 at pH5.5. However MG101 was fully selective for CatS at pH 7.4 (kcat/Km=140,000 M-1.s-1) and sensitive to low concentration of CatS (<1 nM). The selectivity of MG101 was successfully endorsed ex vivo, as it was hydrolysed in cell lysates derived from wild-type but not knockout CatS murine spleen. Furthermore, applicatio...

Source: Biochimie - March 22, 2019 Category: Biochemistry Authors: Wartenberg M, Saidi A, Galibert M, Joulin-Giet A, Burlaud-Gaillard J, Lecaille F, Scott CJ, Aucagne V, Delmas AF, Lalmanach G Tags: Biochimie Source Type: research