Method for determining the activity of the angiotensin-converting enzyme

摘要

A method for determining the activity of an angiotensin-converting enzyme is disclosed comprising the steps of mixing a liquid containing (i) a synthetic substrate X-hippuryl-L-dipeptide having the formula <IMAGE> wherein X represents OH, NH2 or N(CH3)2, and when R1 is H, R2 is H, and when R1 is <IMAGE> R2 is CH2CH(CH3)2, (ii) hippuricase and (iii) 4-aminoantipyrine, with a liquid containing an angiotensin-converting enzyme; measuring colorimetrically the concentration of the quinonimine dye which is formed by adding an oxiding agent to the above mixture; and calculating the activity of the angiotensin-converting enzyme from the concentration of the quinonimine dye.