1. Rat testicular angiotensin I converting enzyme: purification and comparison with rat pulmonary enzyme
T Yamaguchi, M Hiratsuka, M Ikekita, K Kizuki, H Moriya Adv Exp Med Biol. 1986;198 Pt A:461-7. doi: 10.1007/978-1-4684-5143-6_62.
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.
2. Solubilization of angiotensin I-coverting enzyme from rabbit lung using trypsin treatment
K Nishimura, K Hiwada, E Ueda, T Kokubu Biochim Biophys Acta. 1976 Nov 8;452(1):144-50. doi: 10.1016/0005-2744(76)90065-6.
The solubilization of angiotensin I-converting enzyme (peptidyldipeptide hydrolase, EC 3.4.15.1) from rabbit lung was carried out using trypsin treatment. A good recovery of 76% was obtained. The enzyme from solubilized fraction was purified using colums of Sephadex G-200, hydroxyapatite and DEAE-cellulose. The purified enzyme was shown to convert angiotensin I to angiotensin II and also to inactivate bradykinin. The specific activity of the enzyme was 24.3 units/mg protein for hippurylhistidylleucyl hydroxide and 0.182 mumol/min per mg protein for angiotensin I. The enzymic activity obtained after trypsin treatment for 5 h could be divided into two components: (i) an enzyme of molecular weight 300 000 (peak II) and (ii) an enzyme of molecular weight 145 000 (peak III), by Sephadex G-200 gel filtration. The molecular weight of the denatured enzyme was found to be 155 000 by disc gel electrophoresis in the presence of sodium dodecyl sulfate. Km values of peak II and peak III fraction for Hippuryl-His Leu-OH were 2.6 mM.
3. Purification of angiotensin I-converting enzyme from human lung
K Nishimura, N Yoshida, K Hiwada, E Ueda, T Kokubu Biochim Biophys Acta. 1977 Aug 11;483(2):398-408. doi: 10.1016/0005-2744(77)90067-5.
Angiotensin I-converting enzyme (peptidyl dipeptide hydrolase, EC 3.4.15.1) was solubilized from the membrane fraction of human lung using trypsin treatment and purfied using columns of DE 52-cellulose, hydroxyapatite and Sephadex G-200. The purified enzyme was shown to convert angiotensin I to angiotensin II and also to inactivate bradykinin. The specific activity of the enzyme was 9.5 units/mg protein for Hippuryl-His-Leu-OH and 0.665 mumol/min per mg protein for angiotensin I. The enzymic activity obtained after trypsin treatment (1 mg/200 mg protein) for 2 h could be divided into three components: (i) an enzyme of molecular weight 290 000 (peak I), (ii) an enzyme of molecular weight 180 000 (peak II) and (iii) an enzyme of molecular weight 98 000 (peak III), by columns of DE 52-cellulose and Sephadex G-200. Km values of peak I, II and III fraction for Hippuryl-His-Leu-OH were identical at 1.1 mM. pH optimum of the enzyme was 8.3 for Hippuryl-His-Leu-OH.
