Rat testicular angiotensin I converting enzyme: purification and comparison with rat pulmonary enzyme

Enzymological properties of rat testicular angiotensin I converting enzyme (RT-ACE) were compared with those of rat pulmonary angiotensin I converting enzyme (RP-ACE). The molecule of RT-ACE was different from that of RP-ACE with respect to the molecular weight, i.e., the molecular weight of RT-ACE was estimated to be 104 kilo-dalton (kd) and that of RP-ACE (150 kd) on SDS-polyacrylamide gel electrophoresis. On the other hand, the enzymochemical properties of RT-ACE were very similar to those of RP-ACE, with regard to activation by NaCl, optimum pH, Km value for N*-hippuryl-His-Leu-OH hydrolysis and sensitivities to various inhibitors. Therefore, it was speculated that the portions contributing to the appearance of catalytic activity would be similar between RT-ACE and RP-ACE.