Disulfide redox balance in Schistosoma mansoni

描述（由申请方提供）：血吸虫病是一种重要的热带寄生性人类和兽医疾病。虽然一种廉价而高效的抗寄生虫药物正在使用，但仍有2000万人患有严重的疾病症状，传播率变化不大，有证据表明抗药性寄生虫的发展。由于目前没有合适的替代疗法，因此迫切需要开发新的化疗药物。血吸虫在其最终宿主和中间宿主中必须能够在免疫和自身产生的活性氧化合物的存在下存活，并为许多关键的酶促途径提供二硫键还原当量。两个平行的解毒/二硫键还原系统发生在大多数生物体中，一个基于谷胱甘肽，另一个基于硫氧还蛋白。最近的研究结果表明，曼氏血吸虫成虫缺乏谷胱甘肽还原酶和硫氧还蛋白还原酶在这些途径中的关键酶。相反，这些活动被发现在一个单一的蛋白质硫氧还蛋白谷胱甘肽还原酶。本申请提出研究硫氧还蛋白谷胱甘肽还原酶在寄生虫抗氧化防御和氧化还原平衡中的作用。天然蛋白质将被纯化和生化表征。为了进行更广泛的分析，将产生活性重组蛋白。将使用已知的酶抑制剂研究蛋白质在体外和体内氧化还原防御中的作用。将确定酶的阶段和组织表达。由于二硫键氧化还原平衡在染色体是集中在一个单一的，关键的酶，是从根本上不同于主机的机制，我们建议，这条途径是一个有前途的目标，新的，合理的药物设计。

DESCRIPTION (provided by the applicant): Schistosomiasis is an important tropical parasitic human and veterinary disease. Although an inexpensive and highly effective anti-schistosome drug is in use 20 million individuals still suffer severe disease symptoms, transmission rates have changed little and there is evidence for the development of drug resistant parasites. Because there is currently no suitable alternative therapy available, there is an urgent need for the development of novel chemotherapeutic agents. Schistosomes in their definitive and intermediate hosts must be able to survive in the presence of immune and self generated reactive oxygen compounds and provide disulfide-reducing equivalents for a number of critical enzymatic pathways. Two parallel detoxification/disulfide reduction systems occur in most organisms, one based on glutathione and the other based on thioredoxin. Recent results indicate that adult Schistosoma mansoni are deficient in glutathione reductase and thioredoxin reductase key enzymes in these pathways. Instead these activities are found together in a single protein thioredoxin glutathione reductase. This application proposes to investigate the role of thioredoxin glutathione reductase in parasite antioxidant defense and redox balance. The native protein will be purified and biochemically characterized. Active recombinant protein will be produced in order to carry out more extensive analysis. The role of the protein in redox defenses in vitro and in vivo will be investigated using known enzyme inhibitors. The stage and tissue expression of the enzyme will be determined. Because disulfide redox balance in schistosomes is centered on a single, key enzyme and is fundamentally different from host mechanisms we propose that this pathway is a promising target for novel, rational drug design.