Renin is an enzyme that plays a crucial role in the regulation of blood pressure and electrolyte balance by activating the renin-angiotensin-aldosterone system (RAAS). It is secreted by the kidneys in response to low blood pressure or low sodium levels.The activity of recombinant human REN is measured by its ability to cleave a fluorogenic peptide substrate Arg-Glu(EDANS)-Ile-His-Pro-Phe-His-Pro-Phe-His-Leu-Val-Ile-His-Thr-Lys(dabcyl)-Arg
in the assay buffer 50 mM Sodium Acetate, 150 mM NaCl, 2 mM EDTA, pH 5.0 .Recombinant human REN was diluted to 200ug/ml in the activation buffer 5 mM Tris, 15 mM NaCl, 1 mM CaCl2, 0.005% Brij-35, pH 7.5, then activated by Trypsin in a final concentration of 4ug/ml incubated at 37 °C for 1 hours. Stop activation with PMSF at 1 mM and incubate at room temperature for 30 min.The activated rhREN is diluted toto different concentrations in assay buffer. Loading into a black well plate 50 µL rhREN and start the reaction by adding 50 µL of 20 µM substrate, with a substrate blank containing 50 µL assay buffer, 50 µL substrate, and no rhREN.Then read at excitiation and emission wavelengths of350 nm and 490 nm, respectively, in kinetic mode for 5 minutes. The specific activity of rhREN is >13 pmol/min/µg