INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
The role of the CD region in globin Hexacoordination
Autor/es:
LUCIANA CAPECE; ALEJANDRO D. NADRA; AXEL BIDÓN-CHANAL; F. JAVIER LUQUE; MARCELO A. MARTI; DARÍO A. ESTRIN
Lugar:
Antwerpen, Bélgica
Reunión:
Congreso; XVIth International Conference on Oxygen Binding and Sensing Proteins; 2010
Institución organizadora:
University of Antwerpen
Resumen:
In several globins, direct coordination of HisE7 to the Fe atom leads to the formation of a hexacoordinated (6c) globin, as noted in neuroglobin (Ngb), cytoglobin, rice hemoglobin and tomato hemoglobin, among others. On the other hand, myoglobin (Mb)and tetrameric human hemoglobin are relevant examples of pentacoordinated (5c) heme proteins, in which the heme is ready to bind exogenous ligands. In our previous work, we have studied the 5c to 6c transition in wild type Ngb, and analized the main differences between this protein and Mb, observing that the flexibility of the CD region is a key factor in the hexacoordination process.In this work, we have interchanged the CD regions of Mb and Ngb, forming two chimeric proteins. We have studied these chimeric proteins by means of molecular dynamics simulations, and calculated the free energy profiles for the 5c to 6c process.The results indicate that chimeric Mb is able to form the 6c adduct, similarly to wt Ngb. In chimeric Ngb, the reduction of the flexibility in the CD region results in a significant increase of the energy barrier for the 6c→5c transition, as has been previously observed for the process under high pressure conditions. Finally, our results confirm the role of the flexible and disordered CD region in Neuroglobin, confirming its key structural role for the hexacoordination process.