一种固定化三酶系统：线粒体微环境区室化的模型。
An immobilized three-enzyme system: a model for microenvironmental compartmentation in mitochondria.
作者信息
Srere P A, Mattiasson B, Mosbach K
出版信息
Proc Natl Acad Sci U S A. 1973 Sep;70(9):2534-8. doi: 10.1073/pnas.70.9.2534.
An immobilized three-enzyme system, malate dehydrogenase (EC 1.1.1.37)-citrate synthase (EC 4.1.3.7)-lactate dehydrogenase (EC 1.1.1.27), was investigated as a model for the rate of oxalacetate production and utilization in mitochondria. Lactate dehydrogenase is included to mimic the NADH-utilizing system of mitochondria. This three-enzyme system was immobilized in three different ways (1) on Sephadex G-50 (surface coupling), (2) on Sepharose 4B (internal-external coupling), and (3) entrapped in polycrylamide gel. The rate of citrate production from malate, NAD(+), and acetyl CoA was determined continuously in a flow system. Up to about 100% rate enhancements were observed when the immobilized system was compared to identical systems of free enzyme. An even more pronounced increase of rate of up to about 400% compared to the soluble system was measured after addition of pyruvate (to reoxidize formed NADH). These results are interpreted in relation to microenvironmental changes of oxalacetate production and the possible organization of enzymes of the Krebs cycle.
一种固定化三酶体系，即苹果酸脱氢酶（EC 1.1.1.37）-柠檬酸合酶（EC 4.1.3.7）-乳酸脱氢酶（EC 1.1.1.27），作为线粒体中草酰乙酸产生和利用速率的模型进行了研究。加入乳酸脱氢酶是为了模拟线粒体利用NADH的系统。该三酶体系通过三种不同方式固定：（1）固定在葡聚糖G-50上（表面偶联），（2）固定在琼脂糖4B上（内外偶联），以及（3）包埋在聚丙烯酰胺凝胶中。在流动体系中连续测定苹果酸、NAD(+)和乙酰辅酶A生成柠檬酸的速率。与游离酶的相同体系相比，固定化体系的速率提高了约100%。加入丙酮酸（以重新氧化生成的NADH）后，与可溶性体系相比，速率甚至更显著地提高了约400%。这些结果是根据草酰乙酸产生的微环境变化以及三羧酸循环中酶的可能组织来解释的。
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