Linked Life Data

20668762

Source:http://linkedlifedata.com/resource/pubmed/id/20668762

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
35
pubmed:dateCreated
2010-8-27
pubmed:abstractText
The entry of a water molecule into the distal heme pocket of pentacoordinate heme proteins such as myoglobin and the alpha,beta chains of hemoglobin can be detected by time-resolved spectroscopy in the heme visible bands after photolysis of the CO complex. Reviewing the evidence from spectrokinetic studies of Mb variants, we find that this optical method measures the occupancy of non(heme)coordinated water in the distal pocket, n(w), with high fidelity. This evidence further suggests that perturbation of the kinetic barrier presented by distal pocket water is often the dominant mechanism by which active site mutations affect the bimolecular rate constant for CO binding. Water entry into the heme pockets of isolated hemoglobin subunits was detected by optical methods. Internal hydration is higher in the native alpha chains than in the beta chains, in agreement with previous crystallographic results for the subunits within Hb tetramers. The kinetic parameters obtained from modeling of the water entry and ligand rebinding in Mb mutants and native Hb chains are consistent with an inverse dependence of the bimolecular association rate constant on the water occupancy factor. This correlation suggests that water and ligand mutually exclude one another from the distal pockets of both types of hemoglobin chains and myoglobin.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
1463-9084
pubmed:author
pubmed:issnType
Electronic
pubmed:day
21
pubmed:volume
12
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10270-8
pubmed:dateRevised
2011-9-22
pubmed:meshHeading
pubmed:year
2010
pubmed:articleTitle
Kinetic spectroscopy of heme hydration and ligand binding in myoglobin and isolated hemoglobin chains: an optical window into heme pocket water dynamics.
pubmed:affiliation
Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, California 94132, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural