Purine Pathways and Inhibitor Design in Plasmodium

疟原虫中的嘌呤途径和抑制剂设计

基本信息

批准号：
7619060
负责人：
Vern L. Schramm
金额：
$ 48.22万
依托单位：
ALBERT EINSTEIN COLLEGE OF MEDICINE
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-08-01 至 2013-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7619060
关键词：
Adenosine Adenosine Kinase Affinity Anabolism Animal Disease Models Antibiotic Resistance Antimalarials Biochemical Biological Biological Availability Blood Bypass Cause of Death Cell Culture Techniques Cellular biology Cessation of life Chemistry Child Clinical Coformycin Collaborations Communicable Diseases Complex Coupling Crystallography Culicidae Cultured Cells Disease Elements Enzymatic Biochemistry Enzymes Erythrocyte Survival Erythrocytes Generations Genetic Genome Goals Human Hypoxanthines Immucillin-H Infection Inosine Interruption Ions Isotopes Kinetics Label Life Malaria Mass Spectrum Analysis Measures Metabolic Metabolism Methods Mouse Strains Mus Muscle Form Glycogen Phosphorylase Nucleic Acid Precursors Nucleosides Orotate Phosphoribosyltransferase Parasites Pathway interactions Pattern Pharmaceutical Preparations Phosphorylases Physiological Plasmodium Plasmodium falciparum Plasmodium yoelii Purine Nucleoside Phosphorylase Inhibitor Purine Nucleotides Purine-Nucleoside Phosphorylase Purines Pyrimidine Pyrimidine Nucleotides Pyrimidines Radioisotopes Research Resistance Source Specificity Structure Synthesis Chemistry Technology Testing Therapeutic Validation accelerator mass spectrometry adenosine deaminase analog base comparative design enzyme structure frontier hypoxanthine-guanine-xanthine phosphoribosyltransferase in vivo inhibitor/antagonist killings metabolic abnormality assessment mouse model nucleotide metabolism overexpression phosphonate professor programs public health relevance purine pyrimidine analog quantum chemistry research study ribosyltransferase theories uptake

项目摘要

DESCRIPTION (provided by applicant): Plasmodium falciparum is the leading cause of death from malaria, taking the lives of over a million children and causing clinical illness in 300 to 500 million people each year. The parasite has acquired resistance against most antimalarials and new drugs are required. P. falciparum is a purine auxotroph, requiring purine salvage from human erythrocytes for survival. Using the frontier technology of transition state analysis, the transition state structures of P. falciparum purine nucleoside phosphorylase (PNP) and adenosine deaminase (ADA) have been solved and used to design transition state analogue inhibitors to match a their transition states. These inhibitors block their respective pathways and kill parasites cultured in human erythrocytes, but do not cure infections of Plasmodium yoelii in mice, an animal model of the disease. Metabolite labeling patterns and mouse studies have established that new pathways remain to be discovered and targeted. Inhibitor design against two critical targets will be assisted by solving the transition state structures of P. falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT), the most critical step in purine synthesis. In the essential pathway of malarial de novo pyrimidine biosynthesis, orotate phosphoribosyltransferase (OPRT) is the essential first step to form all pyrimidine nucleotides. These transition state structures will be solved by frontier methods coupling kinetic isotope effects and quantum chemistry. A new generation of inhibitors will be patterned on these transition states and tested against parasites cultured in human erythrocytes and in the mouse model of P. yoelii infection. Purine salvage and synthetic pathways in parasites and their interruption with inhibitors will be investigated with purine precursors with specific radioisotope labels. The ultrasensitive method of accelerator mass spectrometry (AMS) will be used to follow normal pathways of purine salvage without perturbing normal pools in cultured cells and in mouse infections. The AMS approach has revealed uncharacterized pathways of purine salvage and these will be defined in metabolic, enzymatic and inhibitor approaches. Antimalarials that block purine salvage or pyrimidine synthesis may be useful therapeutics as single agents or in combination with agents targeted against other pathways. Simultaneous blocking of two targets decreases the ability of mutational escape by the parasite. PUBLIC HEALTH RELEVANCE Malaria is an infectious disease cause by parasites spread by mosquitoes in tropical regions of the developing world. Approximately one million children die each year from the disease and current drugs are losing their efficiency because of acquired antibiotic resistance by the parasites. This research proposes new ways to treat malaria by discovered new ways to kill the parasites without harming the human host and by exploring new drugs.

描述（由申请人提供）：恶性疟原虫是疟疾死亡的主要原因，每年夺走超过 100 万儿童的生命，并导致 300 至 5 亿人出现临床疾病。这种寄生虫已经对大多数抗疟药产生了耐药性，因此需要新的药物。恶性疟原虫是一种嘌呤营养缺陷型，需要从人类红细胞中回收嘌呤才能生存。利用过渡态分析前沿技术，解析了恶性疟原虫嘌呤核苷磷酸化酶（PNP）和腺苷脱氨酶（ADA）的过渡态结构，并用于设计与其过渡态相匹配的过渡态类似物抑制剂。这些抑制剂阻断各自的途径并杀死在人类红细胞中培养的寄生虫，但不能治愈小鼠（该疾病的动物模型）的约氏疟原虫感染。代谢标记模式和小鼠研究表明，新的途径仍有待发现和瞄准。通过解决恶性疟原虫次黄嘌呤-鸟嘌呤-黄嘌呤磷酸核糖基转移酶（HGXPRT）的过渡态结构（嘌呤合成中最关键的步骤），将有助于针对两个关键靶点的抑制剂设计。在疟疾从头嘧啶生物合成的基本途径中，乳清酸磷酸核糖转移酶（OPRT）是形成所有嘧啶核苷酸的必要的第一步。这些过渡态结构将通过耦合动力学同位素效应和量子化学的前沿方法来解决。新一代抑制剂将以这些过渡状态为模式，并针对在人类红细胞和约氏疟原虫感染的小鼠模型中培养的寄生虫进行测试。将使用具有特定放射性同位素标记的嘌呤前体来研究寄生虫中的嘌呤回收和合成途径及其用抑制剂的中断。加速器质谱（AMS）的超灵敏方法将用于追踪嘌呤回收的正常途径，而不干扰培养细胞和小鼠感染中的正常池。 AMS 方法揭示了未表征的嘌呤回收途径，这些途径将通过代谢、酶和抑制剂方法进行定义。阻断嘌呤回收或嘧啶合成的抗疟药作为单一药物或与针对其他途径的药物联合使用可能是有用的治疗方法。同时阻断两个目标会降低寄生虫突变逃逸的能力。公共卫生相关性疟疾是发展中国家热带地区由蚊子传播的寄生虫引起的传染病。每年约有一百万儿童死于这种疾病，并且由于寄生虫获得了抗生素耐药性，目前的药物正在失去效力。这项研究通过发现在不伤害人类宿主的情况下杀死寄生虫的新方法以及探索新药物，提出了治疗疟疾的新方法。