Screening of renin inhibitory activity in Foods and its functional analysis.

肾素-血管紧张素-醛固酮系统（RAS）在动物血压控制中起重要作用。肾素催化血管紧张素I从血浆底物血管紧张素原中释放。所产生的十肽血管紧张素I是一种非活性肽，由血管紧张素转换酶（ACE）激活。ACE从血管紧张素i中分离c端二肽，产生的血管紧张素II通过血管收缩和刺激醛固酮的合成和释放而升高血压。因此，肾素是RAS的关键酶。ACE因其简便的测定方法而被用作RAS中筛选抑制剂的靶酶；然而，肾素在RAS中是一种限速酶，由于测量非常复杂，所以没有使用它。在本研究中，我们在大肠杆菌线圈细胞中表达重组人肾素，并被胰蛋白酶重新折叠和激活。以重组人肾素为靶酶，对发酵豆酱中的肾素抑制活性进行了筛选，发现豆酱的主要成分大豆具有抑制肾素的活性。此外，我们在昆虫Sf-9细胞中表达了重组人肾素，发现在培养后期积累了成熟的活性肾素。利用该培养基对重组人肾素进行了简单纯化，并对其各项性质进行了表征。我们的方法应该利用杆状病毒表达系统提供大量的重组人肾素。

The renin-angiotensin-aldosterone system (RAS) plays an essential role in blood pressure control in animals. Renin catalyzes the liberation of angiotensin I from plasma substrate angiotensinogen. The produced decapeptide angiotensin I is an inactive peptide and activated by angiotensin converting enzyme (ACE). ACE cleaves C-terminal dipeptide from angiotensin I. The produced angiotensin II raises blood pressure by vasoconstriction as well as stimulation of the synthesis and release of aldosterone. Thus, renin is a key enzyme of RAS. ACE has been used as a target enzyme in RAS for screening inhibitors because of its simple assay method; however, renin is a rate-limiting enzyme in RAS, so it was not used because the measurement is very complicated. In the present study, we expressed recombinant human renin in Escherichia coil cells, refolded and activated by trypsin. Using recombinant human renin as a target enzyme, we screened the renin inhibitory activity in fermented soybean paste (miso) and found that soybean, the major ingredient of miso, had renin inhibitory activity. Moreover, we expressed recombinant human renin in insect Sf-9 cells and found that mature active renin accumulated in the late stage of cultivation. Using the medium, we simply purified recombinant human renin and characterized various properties of it. Our method should provide a large quantity of recombinant human renin using the baculovirus expression system.