ASSAY KITS

ELISA

During Enzyme-linked immunosorbent assay (ELISA), an unknown amount of target is specifically immobilized on a solid support (capture of target antibody by a specific antigen; capture of target protein by a specific antibody). Detection is performed using a labeled antibody conjugate, which produces a signal (fluorimetric, colorimetric or luminometric), proportionnal to the quantity of tested compound in the sample.

Enzymatic assay

All enzyme assays measure either the consumption of substrate or production of product over time. The concentration of substrates/products as well as the activity of enzymes can be assayed.

FRET Protease assay

• Fluorescence or Förster resonance energy transfer (FRET) is a distance- dependent transfer of excited state energy from an excited donor (fluorophore) to an acceptor (another fluorophore or quencher). This transfer prevents the fluorophore to emit a fluorescent signal at its emission wavelength. Consequently these assays measure events allowing the physical separation of the fluorophore and the quencher, such as proteolytic cleavage, leading to the release of the fluorescent signal.
• Fluorogenic peptide protease assays also measure the activity of proteases but a fluorogenic peptide is used as a substrate.

FRET + ELISA

FRET technology combined with ELISA assay allows a specific detection of the activity of a particular protease in a biological sample, possibly containing multiple proteases which recognize the same FRET peptide-substrate. The target protease is selectively captured by ELISA, then its activity is assayed using a FRET peptide.