INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The Peculiar Heme Pocket of the Truncated Hemoglobin of an antarctic bacterium
Autor/es:
LEONARDO BOECHI
Lugar:
St Simon Island - USA
Reunión:
Congreso; 50th Sanibel Symposium; 2010
Resumen:
<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } --> Truncated hemoglobins (trHbs) are heme proteins present in bacteria, unicellular eukaryotes, and higher plants. Three phylogenetic groups (N, O, and P) have been identified in trHbs. We studied two truncated hemoglobin belonging to group O and P, in order to explain some experimental results. In the first case, the crystal structure of truncated hemoglobin O of B. subtilis, does not show an evident tunnel/cavity system connecting the protein active site with the solvent, a fact that cannot be easily rationalized considering the very high oxygen association rate. Moreover, resonant Raman results of the CO bound protein, showed that a complex hydrogen bond network exists in the distal cavity, making it difficult to assign unambiguously the residues involved in the stabilization of the bound ligand. In the second case the truncated hemoglobin P of C. jejuni shows three residues in the distal site (His, Tyr, Trp) to stabilize the coordinated oxygen. Intriguingly when one of them (His) is mutated by Leu, the O2 affinity is increased. For these reasons we performed classical molecular dynamics simulations of the oxy, carboxy and deoxy protein in both proteins in order to explain these experimental results. We also performed Multiple Steered Molecular Dynamics to compute the free energy profile for ligand migration, and a classic-quantum approach (QM/MM) in order to compute the binding between O2 and these proteins.