Wallace K B, Bailie M D, Hook J B
Am J Physiol. 1978 Mar;234(3):R141-5. doi: 10.1152/ajpregu.1978.234.3.R141.
Angiontensin-converting enzyme (ACE) catalyzes rapid conversion of angiotensin II (AII). This enzyme has been identified in the vascular endothelium of nearly every tissue. Inasmuch as AII is the biologically active component of the renin-angiotensin system, and since age-related differences exist in the renin-angiotensin system, it was of interest to determine converting enzyme activity during development. ACE activity was quantified by measuring the optical density of hippuric acid liberated from hippuryl-L-histidyl-L-leucine (HHL) following incubation with the 20,000 X g supernatant of tissue homogenates. Pulmonary ACE activity of near-term fetal rats was not different than 1-day-old animals. Therafter, ACE activity increased during the first 6 wk postpartum in a biphasic manner. A similar age-dependent increase in converting enzyme activity was observed in rat kidney, mouse kidney, and mouse lung. Substrate affinity of all enzymes measured was similar, suggesting that the age-related increase in activity was due to increased enzyme content. The low activity of ACE in the newborn might function to limit AII production.
血管紧张素转换酶（ACE）催化血管紧张素II（AII）的快速转化。这种酶已在几乎每个组织的血管内皮中被鉴定出来。由于AII是肾素-血管紧张素系统的生物活性成分，并且由于肾素-血管紧张素系统存在与年龄相关的差异，因此确定发育过程中的转换酶活性很有意义。通过测量与组织匀浆20,000×g上清液孵育后从马尿酰-L-组氨酸-L-亮氨酸（HHL）释放的马尿酸的光密度来定量ACE活性。近足月胎鼠的肺ACE活性与1日龄动物没有差异。此后，产后前6周ACE活性以双相方式增加。在大鼠肾脏、小鼠肾脏和小鼠肺中观察到转换酶活性有类似的年龄依赖性增加。所测量的所有酶的底物亲和力相似，这表明与年龄相关的活性增加是由于酶含量增加所致。新生儿ACE的低活性可能起到限制AII产生的作用。
