Fluorimetric assay of renin

A simple fluorimetric assay was set up to test renin within 2 h. N-acetyltetradecapeptide was synthesized and used as substrate. It was demonstrated that N-acetyl-angiotensin I and Leu-Val-Tyr-Ser were the two peptides obtained after hydrolysis by renin. Fluorescamine reaction reacted with the free NH2 of the tetrapeptide generated to induce a fluorimetric reaction detected at 395--405 nm. The Michaelis constant of the reaction was 1.87 . 10(-5) M. With this method as little as one milliGoldblatt Unit (mG.U.) of hog renin could be detected and the generation of tetrapeptide was linear with respect to the renin concentration up to 20 mG.U. The fluorimetric assay was applied to the detection of renin during its purification and to the characterization of renin inhibitors.