Title
Ligand migration through the internal hydrophobic cavities in human neuroglobin Ligand migration through the internal hydrophobic cavities in human neuroglobin
Author
Faculty/Department
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences . Biomedical Sciences
Publication type
article
Publication
Washington, D.C. ,
Subject
Physics
Human medicine
Source (journal)
Proceedings of the National Academy of Sciences of the United States of America. - Washington, D.C.
Volume/pages
106(2009) :45 , p. 18984-18989
ISSN
0027-8424
1091-6490
ISI
000271637500022
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
Neuroglobin (Ngb), a member of the globin superfamily, was found in the brain of vertebrates and is suggested to play a neuroprotective function under hypoxic conditions by scavenging nitrogen monoxide (NO) through a dioxygenase activity. In order for such a reaction to efficiently take place and to minimize the release of reactive intermediates in the cytosol, the cosubstrates O2 and NO and other unstable reaction intermediates should bind sequentially to docking sites in the protein matrix. We have characterized the accessibility of these sites by analyzing the geminate CO rebinding kinetics to the heme moiety observed upon nanosecond flash photolysis of the Ngb-CO complex encapsulated in silica gels. The geminate rebinding phase showed a remarkable complexity, revealing the presence of a system of secondary docking sites where ligands are stored for hundreds of microseconds. Most kinetics steps display little temperature dependence, demonstrating that ligands can easily migrate through the cavities, except for the slowest reaction intermediate, possibly reflecting a structural conformational change reshaping the system of cavities. This conformational change is unrelated with distal His E7 binding to the heme, as it persists for the HE7L mutant. Overall, data are consistent with the presence of a discrete system of docking sites, possibly acting as reservoirs for the putative cosubstrates and for other reactive species involved in the physiologically relevant reaction.
E-info
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000271637500022&DestLinkType=RelatedRecords&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000271637500022&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000271637500022&DestLinkType=CitingArticles&DestApp=ALL_WOS&UsrCustomerID=ef845e08c439e550330acc77c7d2d848
Handle