L-Pyroglutamyl-L-prolyl-L-valine-p-nitroanilide, a highly specific substrate for granulocyte elastase

L-Pyroglutamyl-L-prolyl-L-valine-p-nitroanilide was found to be a highly specific substrate for human granulocyte elastase. At pH 8.3 and 37 degrees C, its Km = 0.55 mmol/l and the value for kcat was 6 sec-1, whereas with porcine pancreatic elastase these values were approximately 2 mmol/l and less than 0.001 sec-1, respectively. It is not cleaved by trypsin or chymotrypsin. With granulocyte elastase this new substrate is 50 times more sensitive compared to succinyltrialanyl-p-nitroanilide. L-Pyroglutamyl-L-prolyl-L-valine-p-nitroanilide can also be used for the assay of granulocyte elastase inhibitors.