Incomplete correlation between serum ACE concentration and activity.

<p>Serum ACE concentration and specific ACE activity was determined in hypertensive patients (n = 151 patients). Serum ACE concentration was determined by an ELISA method using 100-fold diluted serum samples. Human recombinant ACE was used to construct calibration curves for each individual plate. Serum ACE expression was calculated based on these calibration curves. ACE activity was assessed at a 4-fold dilution by measuring the decomposition of the artificial substrate FAPGG. Serum ACE activity is shown as a function of the serum ACE concentration in the figures. Panel <b>A</b> shows the individual data, while patients were grouped according to their serum ACE concentration in panel <b>B</b>. Both graphs were fitted by a linear regression to reveal correlations between the values, and the parameters of the fits are shown. The magnitude of the differences in ACE concentration and ACE activity values are also shown. Symbols represent the mean (measurements were done at least 3-times), bars are SEM.