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| Author(s): |
Juliana Roberta Torini de Souza
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2012-04-16 |
| Examining board members: |
Humberto D\'Muniz Pereira;
André Luís Berteli Ambrósio;
Glória Regina Franco
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| Advisor: | Humberto D\'Muniz Pereira |
| Abstract | |
The parasitic illness are the leading cause of deaths in developing countries, and receives little or no attention from drug companies to develop therapies. Schistosomiasis mansoni also known as water belly or snail´s disease is a chronic parasitic illness that affects approximately 207 million people worldwide with approximately 6 million in Brazil. Schistosomiasis is treated by the use of drugs that are not-in fact effective for the eradication of the disease, and although their efficiency cause serious side effects. In addition, there are reports of S. mansoni´s resistant strains to these drugs, thus justifying the search for new drugs. The Schistosoma mansoni parasite does not possess the de novo pathway for purine bases biosynthesis and depends entirely on salvage pathways for its purine requirement. Thus this study aimed to determine the catalytic constants and three-dimensional structure of MTAP (EC 2.4.2.28), an enzyme that is involved in purine salvation pathway, and is thus essential to the reproduction of the parasite. The MTAP was heterologously expressed, purified and crystallized. The protein was submitted to kinetic assays in coupled system, to determine the catalytic constants. The protein was crystallized in 100mM Bis-tris or MES pH 6.1-6.5 and 14-18% PEG 3350. The crystals were submitted to diffraction of rays-X in the LNLS and DLS. Data sets were obtained, processed, refined and analyzed. Structures were obtained in apoenzyme form complexed with fosfate, complexed with adenine and sulfate, complexed with tubercidin and sulfate, and with adenine and glycerol in a space group different of the others. Through the secondary structure, it was possible to analyze the active site and obtained preliminary information of the catalytic mechanism of the target enzyme. This study contributes to the complete elucidation of the purine salvation pathway in S. mansoni, and provides basic information for the research of the new drugs. (AU) | |
| FAPESP's process: | 10/03420-2 - Structural and functional characterization of the enzymes Methylthioadenosine phosphorylase and purine nucleoside phosphorylase isoform 2 of Schistossoma Mansoni. |
| Grantee: | Juliana Roberta Torini de Souza Oliveira |
| Support Opportunities: | Scholarships in Brazil - Master |