CoV Protease Substrate-2 IF670,1000tests

From STEMCELL Technologies, this FRET-based peptide substrate is designed for the detection of coronavirus (CoV) main protease (3CLpro) activity, an enzyme that regulates the CoV replication complex and is of interest as a target for therapeutic applications. The substrate is built on a 12-amino-acid sequence (VNSTLQSGLRKM) that carries Tide Quencher™ 5 (TQ5) at the N-terminus and iFluor™ 670 (IF670) at the C-terminus. While the peptide is intact, favourable energetic overlap between the IF670 excited state and the TQ5 absorption quenches IF670 fluorescence; cleavage by CoV 3CLpro dissociates the donor from the quencher and restores fluorescence in proportion to protease activity.

Quoted specifications include an excitation wavelength of 656 nm, an emission wavelength of 670 nm, a cutoff of 660 nm, an extinction coefficient of 250,000 cm⁻¹M⁻¹, a predicted molecular mass of 3067.69 kDa, and a purity of ≥ 95%. The reagent is supplied as a lyophilized solid of blue appearance, prepared by vacuum drying from a dimethylformamide (DMF) solution.

The product is stable at -20 °C and should be protected from prolonged exposure to light. The vial should be centrifuged before opening and reconstituted in DMSO; do not vortex. Working solutions are prepared by diluting 1 in 200 in 20 mM Tris buffer (pH 7.5), with 50 μL of substrate solution used per assay in a 96-well plate. The product is for research use only and is not intended for human or animal diagnostic or therapeutic use unless otherwise stated.