Z-Gly-Pro-Arg-4MβNA

Z-Gly-Pro-Arg-4MβNA is a thrombin substrate that, upon cleavage by thrombin, releases 4-methoxy-2-naphthylamine (4MβNA). This liberated 4MβNA reacts with 5-nitrosalicylaldehyde to form an insoluble yellow fluorescent product, indicating the site of thrombin activity [1].