PURINES & PURINE ANTIMETABOLITES IN MALARIA

嘌呤

• 批准号: 7724080
• 负责人: Vern L. Schramm
• 金额: $ 2.48万
• 依托单位: UNIVERSITY OF CALIF-LAWRNC LVRMR NAT LAB
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7724080
• 关键词: Adenine; Adenosine; Antimetabolites; Blood; Carbon; Computer Retrieval of Information on Scientific Projects Database; Culture Media; DNA; Enzymes; Erythrocytes; Funding; Glycine; Grant; Guanosine; Human; Hypoxanthine; Hypoxanthines; Inosine; Institution; Label; Malaria; Parasites; Pathway interactions; Polyamines; Precipitation; Purine Nucleoside Phosphorylase Inhibitor; Purine-Nucleoside Phosphorylase; Purines; RNA; Research; Research Personnel; Resources; Sampling; Source; Time; United States National Institutes of Health; Xanthines; adenosine deaminase; analog; feeding; killings; purine; purine metabolism; research study; xanthine

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Project Description Malaria parasites are purine auxotrophs, but grow inside human red blood cells where the concentration of purines is hundreds to thousands of time greater than the amount taken up by the parasites. We therefore need a specific and sensitive way to establish the pathways by which precursors from the blood (or culture medium) are incorporated into the parasites. We are using 14C precursors to label the purine pool in parasites growing in human erythrocytes. The purine precursors include inosine, adenosine, guanosine, 5'-methylthioadenosine, hypoxanthine, adenine, xanthine, glycine, and a newly discovered metabolite of purine metabolism in P. falciparum, 5'-methylthioinosine. These RNA and DNA precursors are fed to cultures at levels appropriate for AMS and the RNA and DNA from the parasites isolated by extraction or precipitation. Samples from these experiments are converted into carbon for AMS analysis. Immucillins, powerful inhibitors of purine nucleoside phosphorylase (PNP) are added to establish which precursors flow through this enzyme to be incorporated in RNA and DNA. Recently we found that the malarial PNP is unique in participating in the salvage of inosine, guanosine and 5'-methylthioinosine, a metabolite that arises from the polyamine pathway in P. falciparum, but not its human host. 5'-methylthioinosine arises specifically in the parasite by the action of P. falciparum adenosine deaminase on 5'-methylthioinosine. This provides an adenine salvage function. Our current hypothesis is that parasite PNP and ADA function in two purine salvage cycles. Blocking either enzyme is productive in killing parasites in the absence of added hypoxanthine. We have synthesized powerful transition state analogues for three enzymes, all of which are in the essential purine salvage of P. falciparum PNP.

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