Enzymes of energy metabolism in the bradyzoites and tachyzoites of Toxoplasma gondii
Enzymes of energy metabolism in the bradyzoites and tachyzoites of Toxoplasma gondii
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DOI：
10.1111/j.1574-6968.1996.tb08090.x
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发表时间：
1996-03-15
影响因子：
2.1
通讯作者：
Coombs, GH
中科院分区：
文献类型：
--
作者：
Denton, H;Roberts, CW;Coombs, GH
对刚地弓形虫慢殖子和速殖子形式的磷酸果糖激酶、丙酮酸激酶、乳酸脱氢酶、NAD(+)-和nadh -连接的异柠檬酸脱氢酶和琥珀酸脱氢酶的活性进行了分析。这两个发育阶段都含有高活性的磷酸果糖激酶（焦磷酸特异性，而不是ATP）、丙酮酸激酶和乳酸脱氢酶，这表明两种形式的能量代谢可能以高糖酵解通量为中心，与乳酸生产有关。缓殖子中后两种酶的活性明显较高，表明乳酸的产生在这种发育形式中特别重要。NAD（+）特异性异柠檬酸脱氢酶在寄生虫的两个阶段都没有检测到（并且被证明是衡量慢殖子制备纯度的有用指标），而两种寄生虫形式都含有低活性的NADP（+）连接的异柠檬酸脱氢酶。这些结果与缺乏功能性TCA循环和呼吸链的慢殖子一致，表明该发育阶段对阿托伐醌缺乏易感性。
The bradyzoite and tachyzoite forms of Toxoplasma gondii, purified from infected animals, were analysed for their activities of phosphofructokinase, pyruvate kinase, lactate dehydrogenase, NAD(+)- and NADH-linked isocitrate dehydrogenases, and succinic dehydrogenase. Both developmental stages contained high activities of phosphofructokinase (specific for pyrophosphate rather than ATP), pyruvate kinase and lactate dehydrogenase, suggesting that energy metabolism in both forms may centre around a high glycolytic flux linked to lactate production. The markedly higher activity of the latter two enzymes in bradyzoites suggests that lactate production is particularly important in this developmental form. NAD(+)-specific isocitrate dehydrogenase was not detectable in either stage of the parasite (and proved useful as a measure of the purity of the bradyzoite preparation), whereas both parasite forms contained low activities of NADP(+)-linked isocitrate dehydrogenase. The results are consistent with the bradyzoites lacking a functional TCA cycle and respiratory chain and are suggestive of a lack of susceptibility of this developmental stage to atovaquone.