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。产生的十肽血管紧张素I是一种无活性肽，并由血管紧张素转换酶（ACE）激活。ACE从血管紧张素I切割C-末端二肽。所产生的血管紧张素II通过血管收缩以及刺激醛固酮的合成和释放来升高血压。因此，肾素是RAS的关键酶。ACE因其测定方法简单而被用作RAS中的靶酶，用于筛选抑制剂;然而，肾素是RAS中的限速酶，因此由于测量非常复杂而未被使用。在本研究中，我们在大肠杆菌细胞中表达重组人肾素，用胰蛋白酶复性和激活。以重组人肾素为靶酶，对发酵大豆酱中的肾素抑制活性物质进行筛选，发现大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，发现成熟的活性肾素在培养后期积累。利用该培养基，我们简单地纯化了重组人肾素，并对其进行了各种性质的表征，为利用杆状病毒表达系统大量生产重组人肾素奠定了基础。

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.