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Title: CO rebinding kinetics and molecular dynamics simulations highlight dynamic regulation of internal cavities in human cytoglobin
Author: Gabba, Matteo
Abbruzzetti, Stefania
Spyrakis, Francesca
Forti, Flavio
Bruno, Stefano
Mozzarelli, Andrea
Luque Garriga, F. Xavier
Viappiani, Cristiano
Cozzini, Pietro
Nardini, Marco
Germani, Francesca
Bolognesi, Martino
Moens, Luc
Dewilde, Sylvia
Keywords: Bioquímica
Biologia molecular
Cinètica enzimàtica
Molecular biology
Enzyme kinetics
Issue Date: 4-Jan-2013
Publisher: Public Library of Science (PLoS)
Abstract: Cytoglobin (Cygb) was recently discovered in the human genome and localized in different tissues. It was suggested to play tissue-specific protective roles, spanning from scavenging of reactive oxygen species in neurons to supplying oxygen to enzymes in fibroblasts. To shed light on the functioning of such versatile machinery, we have studied the processes supporting transport of gaseous heme ligands in Cygb. Carbon monoxide rebinding shows a complex kinetic pattern with several distinct reaction intermediates, reflecting rebinding from temporary docking sites, second order recombination, and formation (and dissociation) of a bis-histidyl heme hexacoordinated reaction intermediate. Ligand exit to the solvent occurs through distinct pathways, some of which exploit temporary docking sites. The remarkable change in energetic barriers, linked to heme bis-histidyl hexacoordination by HisE7, may be responsible for active regulation of the flux of reactants and products to and from the reaction site on the distal side of the heme. A substantial change in both protein dynamics and inner cavities is observed upon transition from the CO-liganded to the pentacoordinated and bis-histidyl hexacoordinated species, which could be exploited as a signalling state. These findings are consistent with the expected versatility of the molecular activity of this protein.
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It is part of: PLoS One, 2013, vol. 8, num. 1, p. e49770-
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ISSN: 1932-6203
Appears in Collections:Articles publicats en revistes (Nutrició, Ciències de l'Alimentació i Gastronomia)

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