N-[3-(2-furyl)acryloyl]-L-phenylalanylglycylglycine (FAPGG) have the maximum absorption peak at 340 nm, angiotensin converting enzyme catalyze N-(3[2-Furyl ]Acryloyl)-Phe-Gly-Gly to produce FAP and GG, and the absorbance at 340 nm will be decreased. The activity of ACE1 can be calculated indirectly by measuring the decrease in absorbance at 340 nm.
