The development and assay performance of a direct kinetic fluorimetric assay for angiotensin-converting enzyme is described. It is based on the substrate developed by Carmel et al. (Clin Chim Acta 1979; 93: 215–20), and applied to a microcentrifugal analyser with fluorescence optics. The method is sufficiently sensitive and precise to detect both normal and pathological activities; the method is linear up to at least three times the upper limit of the reference range. The method correlates well with an established method. Because of interference, the method is unsuitable for use with icteric or haemolysed samples.
References
1.
FanburgBL. Serum angiotensin-1 converting enzyme in the diagnosis and determination of activity of sarcoidosis. In: FanburgBL, ed. Sarcoidosis and Other Granulomatous Diseases of the LungNew York: Marcel Dekker, 1983; 263–72.
CushmanDWCheungHS. Spectrophotometric assay and properties of the angiotensin-converting enzyme of rabbit lung. Biochem Pharmacol1971; 20: 1637–48.
4.
FriedlandJSilversteinE. A sensitive fluorimetric assay for serum angiotensin-converting enzyme. Am J Clin Path1976; 60: 416–26.
5.
KasaharaYAshiharaY. Colorimetry of angiotensin-1 converting enzyme activity in serum. Clin Chem.1981; 27: 1922–5.
6.
PerssonAVRussoSFWilsonIB. A new chromogenic substrate for angiotensin-converting enzyme. Anal BioChem.1978; 91: 674–83.
7.
NeelsHMvan SandeMEScharpeSL. Sensitive colorimetric assay for angiotensin converting enzyme in serum. Clin Chem.1983; 29: 1399–403.
8.
PardueHL. A comprehensive classification of kinetic methods of analysis used in clinical chemistry. Clin Chem.1977; 23: 2189–201.
9.
CarmelAEhrlich-RogzinskySYaronA. A fluorimetric assay for angiotensin-1 converting enzyme in human serum. Clin Chim Acta1979; 93: 215–20.
10.
CushmanDWCheungHSSaboEF, Development of specific inhibitors of angiotensin-I converting enzyme (kininase II). Fed Proc1979; 38: 2778–82.
11.
Ronca-TestoniS. Direct spectrophotometric assay for angiotensin converting enzyme in serum. Clin Chem.1983; 29: 1093–6.
12.
CarmelAYaronA. An intramolecularly quenched fluorescent tripeptide as a fluorogenic substrate of angiotensin-I converting enzyme and of a bacterial dipeptidyl carboxy-peptidase. Eur J BioChem.1978; 87: 265–73.
13.
GuilbaultGG. Practical Fluorescence. New York: Marcel Dekker, 1973; 1–28.
