Renin (EC 3.4.23.15), also known as an angiotensinogenase, is an enzyme that participates in the renin-angiotensin system (RAS) which mediates extracellular volume (i.e. blood plasma, lymph and interstitial fluid), and arterial vasoconstriction. An over-active renin-angiotensin system leads to vasoconstriction and retention of sodium and water, causing hypertension. Renin inhibitors are widely used for the treatment of hypertension. BioVision's Renin inhibitor screening Kit uses a synthetic peptide substrate with a fluorophore (EDANS) at one end and a quencher (DABCYL) at the other end. Renin catalyzes the cleavage of FRET substrate resulting in a product that is detected fluorometrically at Ex/Em = 328/552 nm. In the presence of a Renin in