人红细胞醛糖还原酶的活化形式与非活化形式。
Activated and unactivated forms of human erythrocyte aldose reductase.
作者信息
Srivastava S K, Hair G A, Das B
出版信息
Proc Natl Acad Sci U S A. 1985 Nov;82(21):7222-6. doi: 10.1073/pnas.82.21.7222.
Aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21) has been partially purified from human erythrocytes by DEAE-cellulose (DE-52) column chromatography. This enzyme is activated severalfold upon incubation with 10 microM each glucose 6-phosphate, NADPH, and glucose. The activation of the enzyme was confirmed by following the oxidation of NADPH as well as the formation of sorbitol with glucose as substrate. The activated form of aldose reductase exhibited monophasic kinetics with both glyceraldehyde and glucose (Km of glucose = 0.68 mM and Km of glyceraldehyde = 0.096 mM), whereas the native (unactivated) enzyme exhibited biphasic kinetics (Km of glucose = 9.0 and 0.9 mM and Km of glyceraldehyde = 1.1 and 0.14 mM). The unactivated enzyme was strongly inhibited by aldose reductase inhibitors such as sorbinil, alrestatin, and quercetrin, and by phosphorylated intermediates such as ADP, glycerate 3-phosphate, glycerate 1,3-bisphosphate, and glycerate 2,3-trisphosphate. The activated form of the enzyme was less susceptible to inhibition by aldose reductase inhibitors and phosphorylated intermediates.
已通过DEAE-纤维素（DE-52）柱色谱法从人红细胞中部分纯化了醛糖还原酶（醛糖醇：NADP + 1-氧化还原酶，EC 1.1.1.21）。该酶在与10 microM的6-磷酸葡萄糖、NADPH和葡萄糖一起孵育后被激活了几倍。通过跟踪NADPH的氧化以及以葡萄糖为底物的山梨醇的形成来确认该酶的激活。醛糖还原酶的激活形式对甘油醛和葡萄糖均表现出单相动力学（葡萄糖的Km = 0.68 mM，甘油醛的Km = 0.096 mM），而天然（未激活）酶表现出双相动力学（葡萄糖的Km = 9.0和0.9 mM，甘油醛的Km = 1.1和0.14 mM）。未激活的酶受到醛糖还原酶抑制剂（如山梨醇、醛糖还原酶抑制剂和槲皮素）以及磷酸化中间体（如ADP、3-磷酸甘油酸、1,3-二磷酸甘油酸和2,3-三磷酸甘油酸）的强烈抑制。该酶的激活形式对醛糖还原酶抑制剂和磷酸化中间体的抑制作用较不敏感。
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