Kinetic parameters of serum and lung tissue angiotensin-converting enzyme in patients with lung cancer

Angiotensin-converting enzyme activity and its kinetic parameters were determined in both serum and lung tissue samples obtained from 17 patients with lung cancer and 21 control subjects, regardless of ethical base. The specific activities for cancerous and normal lung tissues were 67.2 +/- 27.3 (mean +/- SD) U/g protein and 28.5 +/- 5.4 U/g protein, respectively (P less than 0.001). Serum enzyme activity, on the other hand, was found to be higher in controls (198 +/- 42 U/L) than in patients (237 +/- 68 U/L) (P less than 0.01). The effects of chloride and zinc ions, pH and temperature on the enzyme activity were investigated as kinetic parameters in both serum and tissue samples.