ROLE OF NADH-FUMARATE REDUCTASE IN TRYPANOSOMA BRUCEI

描述(摘自申请者摘要)：锥虫 克氏锥虫和布氏锥虫引起查加斯病和 分别是非洲昏睡病。几乎没有付出什么努力 确定新的靶点以开发针对这些疾病的合理疗法 疾病。申请人发现，几种锥虫菌株 含有一种哺乳动物没有的酶(NADH-富马酸还原酶)，它 产生琥珀酸，并允许克雷布斯循环的一部分在 倒车。在许多锥虫中，琥珀酸具有双重作用，作为一种 分泌到细胞外环境的代谢终产物，并作为 具有完整呼吸的细胞的重要呼吸底物 链(上鞭毛体或原环体鞭毛体)。申请人 认为琥珀酸在T。 Brucei，并打算表征富马酸的代谢作用 作为一种生产琥珀酸酶的还原酶。这种酶也存在于 血流形式(呼吸链不活跃)，但其 这些形式中的生理作用尚不清楚。富马酸还原酶 最初被认为与膜组分有关。这个 然而，申请人已经发现，这种酶可以在高温下溶解。 离子强度，这是通向纯化的第一步。申请人 建议：1)从布氏毛霉菌中分离纯化并研究该酶 锥虫和原环类鞭毛虫；2)表征四个 纯化酶的有效抑制物；3)测定代谢 该酶在布氏毛滴虫中间代谢中的作用 原环类鞭毛虫通过监测底物积累，琥珀酸 以葡萄糖和脯氨酸为底物生产和NAD(P)H氧化， 4)研究其在细胞内的定位。

DESCRIPTION (Adapted from Applicant's Abstract): The trypanosomatids Trypanosoma cruzi and the T. brucei group cause Chagas' disease and African sleeping sickness, respectively. Little effort is being placed on identifying new targets for developing a rational therapy against these diseases. The applicant has found that several strains of Trypanosoma contain an enzyme not present in mammals (NADH-fumarate reductase) which produces succinate, and allows a section of the Krebs' cycle to operate in reverse. In many trypanosomatids, succinate has a dual role, as a metabolic end product secreted to the extracellular environment and as an important respiratory substrate for cells with a complete respiratory chain (epimastigotes or procyclic trypomastigotes). The applicant believes succinate has a central role in intermediate metabolism of T. brucei, and intends to characterize the metabolic role of fumarate reductase as a succinate-producing enzyme. This enzyme is also present in bloodstream forms (in which the respiratory chain is not active), but its physiological role in these forms is unknown. Fumarate reductase was initially thought to be associated to the membrane fraction. The applicant has found, however, that this enzyme may be solubilized at high ionic strength, a first step towards its purification. The applicant proposes to: 1) purify and study this enzyme from T. brucei trypomastigotes and from procyclic trypomastigotes; 2) characterize four available inhibitors of the purified enzyme; 3) determine the metabolic function of this enzyme in the intermediate metabolism of T. brucei procyclic trypomastigotes by monitoring substrate accumulation, succinate production and NAD(P)H oxidation with glucose and proline as substrates, and 4) investigate its intracellular localization.