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| Author(s): |
Marcelo Santos Castilho
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Carlos. , gráficos, ilustrações, tabelas. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física de São Carlos (IFSC/BT) |
| Defense date: | 2004-02-27 |
| Examining board members: |
Glaucius Oliva;
Eliezer Jesus de Lacerda Barreiro;
Richard Charles Garratt;
Carlos Alberto Montanari;
Monica Tallarico Pupo
|
| Advisor: | Glaucius Oliva |
| Field of knowledge: | Biological Sciences - Biophysics |
| Indexed in: | Banco de Dados Bibliográficos da USP-DEDALUS; Biblioteca Digital de Teses e Dissertações - USP |
| Location: | Universidade de São Paulo. Biblioteca do Instituto de Física de São Carlos; IFSC-F/Te1577 |
| Abstract | |
Aiming at discover molecules with good inhibitory activity against tripanosomatides enzymatic targets, the crystallographic structures of glyceraldehydes-3-phosphate dehydrogenase in complex with 1,3 bisfosfoglyceric acid analogues (30 and 33)were solved, molecular modeling studies were undertaken and xprt (xanthine phosphorybosil transferase) gene from Leishmania major was cloned and over-expressed in Escherichia coli. The enzyme thus obtained was purified and kinetically characterized. .gGAPDH-33 complex, up to 2,5A resolution revealed the tioketal intermediate binding mode. The final model was refined to R 0.20 from a 97,5% completeness dataset. The crystallographic structure gives, for the first time, experimental evidence for the flip-flop mechanism, which describes how the substrate goes from inorganic-phosphate binding site to substratephosphate binding site. gGAPDH-30 complex, solved to 2,75A resolution, revealed the inhibitor binding mode. The final model has R= 0,19 and was refined from a 92,4% completeness dataset. This structure was used as the framework upon which modeling studies were performed. Modeling results suggest why these inhibitors show a different inhibitory profile against Trypanosoma brucei and Trypanosoma cruzi. L. major XPRT shows a high affinity for hypoxanthine, an alternative substrate, when compared to L. donovani XPRT, aiming at understand this behavior homology modeling studies are currently under progress. (AU) | |
| FAPESP's process: | 00/01688-6 - Rational design of anti-trypanosomatid drugs: T. cruzi gGAPDH and L. tarantolae XPRT |
| Grantee: | Marcelo Santos Castilho |
| Support Opportunities: | Scholarships in Brazil - Doctorate |