Caracterização Estrutural das enzimas Acil-Coa Tioesterase 6 de Homo Sapiens, Álcool Desidrogenase de Naegleria gruberi e Gliceraldeído-3-Fosfato Desidrogenase de Paracoccidioides lutzii

Abstract

The structural characterization of enzymes participating in metabolic pathways in pathogenic organisms or of similar genera can help the design of inhibitors. Thus, the

present work aimed to characterize the three dimensional structures of human Acyl- CoA Thioesterase 6, Alcohol Dehydrogenase from Naegleria gruberi and

Glyceraldehyde-3-Phosphate Dehydrogenase from Paracoccidioides lutzii. It should be noted that the first participates in the metabolic regulation of lipids in humans, the second participates in the alcoholic fermentation pathway of the protozoan Naegleria gruberi and the third participates in the glycolytic pathway of Paracoccidioides lutzii. For both Acyl-CoA Thioesterase 6 and Alcohol Dehydrogenase some expression tests were carried out and their structures were modeled by homology. Glyceraldehyde-3-Phosphate Dehydrogenase had its structure solved experimentally by X-Ray Crystallography at 2.02 Å resolution, which was deposited in the PDB with code 8DE5. This is the only GAPDH that has the hydrophilic stretch HSSSNN (residues 61-66), which presents a hydrogen bond network which possibly affects the hairpin motif conformation at the end of this stretch. Thus, this feature might assist the differential design of inhibitors. Furthermore, the structure was co-crystallized with its cofactor NAD+

, with a sulfate ion and with D-galactonic acid. It is the first GAPDH to present a D-galactonic acid and it is speculated if this ligand came from the action of enzyme itself. Finally, structural comparisons indicated that D-galactonic acid is in the new Pi site and the sulfate ion is in the Ps site. The structure was also used to make considerations about differences to the corresponding human enzyme.