pyru-vate (Figure 45–17). A second

pyru-vate (Figure 45–17). A second enzyme, phospho- enolpyruvate carboxykinase, catalyzes the decarboxy- lation and phosphorylation of oxaloacetate to phospho- enolpyruvate using GTP (or ITP) as the phosphate donor. Thus, reversal of the reaction catalyzed by pyru- vate kinase in glycolysis involves two endergonic reac- tions.
In pigeon, chicken, and rabbit liver, phospho- enolpyruvate carboxykinase is a mitochondrial enzyme, and phosphoenolpyruvate is transported into the cy- tosol for gluconeogenesis. In the rat and the mouse, the enzyme is cytosolic. Oxaloacetate does not cross the mi- tochondrial inner membrane; it is converted to malate, which is transported into the cytosol, and converted back to oxaloacetate by cytosolic malate dehydrogenase. In humans, the guinea pig, and the cow, the enzyme is equally distributed between mitochondria and cytosol.
The main source of GTP for phosphoenolpyruvate carboxykinase inside the mitochondrion is the reaction of succinyl-CoA synthetase (Chapter 16). This provides a link and limit between citric acid cycle activity and the extent of withdrawal of oxaloacetate for gluconeo- genesis.

Kết quả (Trung) 2:

pyru-瓦泰岛（图45-17）。第二种酶，磷酸羧enolpyruvate，催化decarboxy-特征研和草酰乙酸，以磷酸用enolpyruvate GTP（或ITP）作为磷酸供体的磷酸化。因此，通过在糖酵解pyru-瓦泰岛激酶催化的反应的逆转涉及两个吸能电抗系统蒸发散。
在鸽子，鸡和兔肝脏，磷酸enolpyruvate羧是线粒体酶，和磷酸被输送到用于糖原异生的CY- tosol 。在大鼠和小鼠中，酶是细胞内。草酰乙酸不越过微tochondrial内膜; 它被转换成苹果酸盐，其中被输送到胞质溶胶，并通过胞质苹果酸脱氢酶转化回草酰乙酸。在人类中，豚鼠，以及牛，酶同等线粒体和胞液之间分配。
GTP对线粒体内磷酸烯醇丙酮酸羧的主要来源是琥珀酰-CoA合成酶（第16章）的反应。这提供了三羧酸循环活性和草酰乙酸停药gluconeo-发生的程度之间的联系和限制。

Kết quả (Trung) 3:

pyru私人（图45–17）。第二酶磷酸烯醇式丙酮酸羧激酶，催化，脱羧法和生成草酰乙酸，磷酸化的磷酸化植物使用GTP（或ITP）作为磷酸供体。因此，该反应由丙-激酶催化糖酵解率逆转涉及两吸能反应。在鸽子、鸡、兔肝、磷酸烯醇式丙酮酸羧激酶是一种线粒体酶和磷酸烯醇式丙酮酸进入赛扬tosol糖异生。在大鼠和小鼠中，酶是胞浆内的。草酰乙酸不能通过线粒体膜内糜；它转化为苹果酸，并运送到细胞质中，并转换成草酰乙酸通过苹果酸脱氢酶。在人类，豚鼠和牛，酶同样分布在线粒体和细胞质之间。对磷酸烯醇式丙酮酸羧化酶在线粒体的主要GTP源琥珀酰辅酶A合成酶反应（16章）。这提供了一个链接和极限之间的柠檬酸循环活性和草酰乙酸为gluconeo退出程度的成因。