Iwata Hideyuki, Nakagawa Tsutomu, Yoshioka Yuichiro, Kagei Kazufumi, Imada Kenta, Nakane Chiaki, Fujita Hiromi, Suzuki Fumiaki, Nakamura Yukio
United Graduate School of Agricultural Science, Gifu University, Yanagido, Gifu, Japan.
Biosci Biotechnol Biochem. 2008 Jan;72(1):179-85. doi: 10.1271/bbb.70541. Epub 2008 Jan 7.
The pH dependence and kinetics parameters of renin-angiotensinogen reactions were determined using wild-type and S84G mutant human renins and wild-type and H13Y mutant sheep angiotensinogens. It is explained in this report that (i) renin catalyzes acidic and basic reactions of which the optimum pHs are 5.5 and 7.5-8.2 respectively, both of which produce angiotensin I; (ii) Ser84 specific to human renin accelerates the acidic reaction by 75-110% through elevation of V(max), and shifts the optimum pH of the basic reaction from 7.5 to 8.0-8.2; and (iii) His13 specific to sheep angiotensinogen accelerates the acidic and basic reactions by 25-42% through reduction of K(m). It is concluded from these results that the coexistence of Ser84 in renin and His13 in angiotensinogen brings a pH profile of two separate peaks at pHs 5.5 and 8.2 to the reaction of human renin and sheep angiotensinogen.
使用野生型和S84G突变型人肾素以及野生型和H13Y突变型绵羊血管紧张素原，测定了肾素 - 血管紧张素原反应的pH依赖性和动力学参数。本报告解释了：（i）肾素催化酸性和碱性反应，其最佳pH分别为5.5和7.5 - 8.2，两者均产生血管紧张素I；（ii）人肾素特有的Ser84通过提高Vmax使酸性反应加速75 - 110%，并将碱性反应的最佳pH从7.5变为8.0 - 8.2；（iii）绵羊血管紧张素原特有的His13通过降低Km使酸性和碱性反应加速25 - 42%。从这些结果得出结论，肾素中的Ser84和血管紧张素原中的His13共存，使得人肾素与绵羊血管紧张素原反应在pH 5.5和8.2处呈现两个独立峰的pH图谱。
