Glycine-1-14C]hippuryl-L-histidyl-L-leucine: a substrate for the radiochemical assay of angiotensin converting enzyme.

Glycine-1-¹⁴C]hippuryl-l-histidyl-l-leucine was synthesized and evaluated as a substrate for the radiochemical assay of angiotensin converting enzyme. Hydrolysis is measured by quantitation of the liberated glycine-1-¹⁴C]hippuric acid by liquid seintillation counting and is linear up to 30% hydrolysis. The advantages of the radiochemical assay over the spectrophotometric quantitation of the liberated hippuric acid are its increased sensitivity and lack of interference by nonionic detergents or lipids.