A rapid and simple spectrophotometric assay of angiotensin-converting enzyme

✍ Scribed by Makoto Hayakari; Yoshikazu Kondo; Hiroshi Izumi

• Publisher: Elsevier Science
• Year: 1978
• Tongue: English
• Weight: 425 KB
• Volume: 84
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(78)90053-2

✦ Synopsis

A rapid, simple, and accurate method for the chemical assay of angiotensin-converting enzyme has been developed. The method relies on previously published method for spectrophotometric assay of angiotensinconverting enzyme activity and on the use of 2,4,6-trichloro-s-triazine (TT) as a calorimetric reagent of hippuric acid (N-benzoylglycine).

When 3% TT in dioxane was added to the incubation medium of the angiotensin-converting enzyme after stopping the incubation by the immersion of the test tubes in a boiling-water bath, the absorbance at 382 nm increased linearly as a function of both enzyme concentration and incubation time. Neither hippuryl-L-histidyl-tleucine (HHL, substrate for this assay system) nor histidyl-leucine was positive in color reaction with TT. Accordingly, this method does not require any procedures for separation of hippuric acid from HHL. The enzyme activity was found to be highest at pH 8.3, at chloride ion concentration of 600 mM, and at HHL concentration of 3 mM. when the SOOOg supematant fluid of the rat lung was used.