Methodological aspects of the use of furanacryloyl-phenylalanyl-glycyl-glycine for the photometric detection of angiotensin converting enzyme activity

Photometric evaluation of serum activity of angiotensin-converting enzyme (ACE) making use of synthetic chromogenic substrate N-(3-[2-furyl]acryloyl)-phe-gly-gly (FAPGG) is analyzed. Spectral characteristics of FAPGG are investigated. The Burger-Lambert-Bar dependence is not observed in any of the working concentrations. Extension of the spectral weight band is associated with the appearance of the absorbency/concentration linear function for FAPGG solution. Under such conditions the registered intensity of the analyzer sign (delta OD/min) is in strong correlation with the spectral weight band. As a result, high inter-analyzer variations were observed. This impedes the standardization of the method and prompts the use of attested calibrators. Linear function of analyzer's sign and ACE level is theoretically achieved at FAPGG concentration 1.0 +/- 0.2 mM (Km = 0.35 +/- 0.05 mM, minimum saturation concentration 1.4 +/- 0.2 mM). Synthetic ACE inhibitors are recommended to rule out the interference.     

Change in activity of angiotensin-converting enzyme in pneumonia and chronic obstructive lung diseases

AIM: To study the activity of angiotensin-converting enzyme (ACE) in patients with pneumonia and chronic obstructive lung diseases (COLD). MATERIAL AND METHODS: Sixty nine patients with pneumonia and 77 with COLD were examined. The activity of ACE in the serum and bronchoalveolar lavage (BAL) and the effects of leukocytic elastase and concentrations of zinc, endogenous inhibitors, and activators were studied. RESULTS: The patients with pneumonia in the acute phase of the disease have been found to have low ACE activity in both blood and BAL. As the inflammatory process comes to an end, ACE activity normalizes. In the patients with COLD, the activity of ACE is primarily decreased at remission. When COLD aggravates, the activity of ACE in blood and BAL increases. In pneumonia and COLD, the changes in ACE activity are more profound in BAL than in blood. CONCLUSION: The only cause of the altered activity of ACE in patients with COLD and pneumonia is a change in the concentration of the enzyme.