Lanzillo J J, Fanburg B L
Biochim Biophys Acta. 1976 Aug 12;445(1):161-8. doi: 10.1016/0005-2744(76)90169-8.
The angiotensin I-coverting enzyme (peptidyldipeptide hydrolase, EC 3.4.15.1) was isolated from both guinea pig lung and serum; Km and V values were determined using both angiotensin I and hippurylhistidylleucine as substrates. Km values for the lung enzyme were 3.1 mM for hippurylhistidylleucine hippurylhistidylleucine and 0.076 mM for angiotensin I. Inhibition studies were performed and I50 values were obtained with the following inhibitors: angiotensin II (lung, 1.9 - 10(-5) M; serum, 1.7 - 10(-5) M), bradykinin (lung, 2.6 - 10(-6) M; serum, 2.1 - 10(-6) M), and pyrrolidone-Lys-Trp-Ala-Pro (lung, 7.9 - 10(-8) M; serum, 5.6 - 10(-8) M). Both enzymes were glycoproteins and were inhibited by concanavalin A. A maximum inhibition of 35% initial enzymatic activity was observed for both enzymes at a concanavalin A concentration of 4 - 10(-4) M suggesting that the sugar moieties of each enzyme are similar. Both enzymes required NaCl for activity and were inhibited by EDTA. A comparison of kinetic and inhibition properties indicates that both enzymes are quite similar.
血管紧张素I转换酶（肽基二肽水解酶，EC 3.4.15.1）是从豚鼠肺和血清中分离得到的；以血管紧张素I和马尿酰组氨酰亮氨酸作为底物测定了Km值和V值。肺酶对马尿酰组氨酰亮氨酸的Km值为3.1 mM，对血管紧张素I的Km值为0.076 mM。进行了抑制研究，并获得了以下抑制剂的I50值：血管紧张素II（肺，1.9×10⁻⁵ M；血清，1.7×10⁻⁵ M）、缓激肽（肺，2.6×10⁻⁶ M；血清，2.1×10⁻⁶ M）和吡咯烷酮-赖氨酸-色氨酸-丙氨酸-脯氨酸（肺，7.9×10⁻⁸ M；血清，5.6×10⁻⁸ M）。两种酶均为糖蛋白，且被伴刀豆球蛋白A抑制。在伴刀豆球蛋白A浓度为4×10⁻⁴ M时，两种酶的初始酶活性均出现了最大35%的抑制，这表明每种酶的糖部分相似。两种酶的活性均需要NaCl，且被EDTA抑制。动力学和抑制特性的比较表明两种酶非常相似。
