Jijakli H, Rasschaert J, Nadi A B, Leclercq-Meyer V, Sener A, Malaisse W J
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Arch Biochem Biophys. 1996 Mar 15;327(2):260-4. doi: 10.1006/abbi.1996.0119.
The activities of hexokinase isoenzymes, lactate dehydrogenase, cytosolic NAD-linked glycerophosphate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, and glutamate dehydrogenase were measured in homogenates of rat purified pancreatic B and non-B islet cells. In B cell homogenates, the maximal activity of hexokinase and glucokinase was one to two orders of magnitude lower than that of lactate dehydrogenase. The activity of the mitochondrial FAD-linked glycerophosphate dehydrogenase was also much lower than that of the cytosolic NAD-linked glycerophosphate dehydrogenase . A comparable hierarchy in the activity of these enzymes was observed in non-B islet cells. These findings reinforce the view that the preferential stimulation of oxidative glycolysis observed in insulin-producing cells, when exposed to high concentrations of D-glucose, is attributable to a Ca2+-induced activation of the mitochondrial FAD-linked glycerophosphate dehydrogenase, rather than to saturation of the catalytic activity of lactate dehydrogenase.
在大鼠纯化的胰腺β细胞和非β胰岛细胞的匀浆中，测定了己糖激酶同工酶、乳酸脱氢酶、胞质NAD连接的甘油磷酸脱氢酶、线粒体FAD连接的甘油磷酸脱氢酶和谷氨酸脱氢酶的活性。在β细胞匀浆中，己糖激酶和葡萄糖激酶的最大活性比乳酸脱氢酶低1至2个数量级。线粒体FAD连接的甘油磷酸脱氢酶的活性也远低于胞质NAD连接的甘油磷酸脱氢酶的活性。在非β胰岛细胞中也观察到了这些酶活性的类似等级关系。这些发现强化了这样一种观点，即当暴露于高浓度D-葡萄糖时，在胰岛素产生细胞中观察到的氧化糖酵解的优先刺激，归因于Ca2+诱导的线粒体FAD连接的甘油磷酸脱氢酶的激活，而不是乳酸脱氢酶催化活性的饱和。
