Introduction to the FLISP Kits

FLISP stands for Fluorescence Labeled Inhibitors of Serine Proteases

Serine Proteases are a family of proteolytic enzymes, in which serine is used as the nucleophilic amino acid within the active site (Hedstrom L. Serine protease mechanism and specificity. Chem Rev. 2002 Dec;102(12):4501-24). If there is an active chymotrypsin-like enzyme inside the cell, it will covalently bind with the FLISP inhibitor.

CMK-based inhibitors: CMK stands for 2,6-diChlorobenzoyloxyMethylKetone, target the catalytic-sites of serine proteases. When included as the reactive-group component of an artificial protease substrate/inhibitor probe, it facilitates the covalent labelling of intracellular chymotrypsin-like protease enzymes. Specificity for this family of intracellular proteases is determined by the inclusion of an amino acid targeting peptide. For example, Leu-CMK and Phe-CMK would inhibit different chymotrypsin-like proteases. DAP (o,p-dichloroacetophenone, PDK1 inhibitor) reactive groups can be used as an alternative to CMK .

ICT’s FLISP kits use either FAM (Excitation/Emission: 488 nm / 520 nm (green)) or sulforhodamine 101 (Excitation/Emission: 590 nm / 610 nm (red)) as the fluorophore labels on the Leu-CMK, Phe-CMK and the Leu-DAP and Phe-DAP inhibitors to quantify Chymotrypsin-like activity.