Linked Life Data

12121767

Source:http://linkedlifedata.com/resource/pubmed/id/12121767

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2002-7-17
pubmed:abstractText
Combined quantum chemical and molecular mechanics geometry optimisations have been performed on myoglobin without or with O(2) or CO bound to the haem group. The results show that the distal histidine residue is protonated on the N(epsilon 2) atom and forms a hydrogen bond to the haem ligand both in the O(2) and the CO complexes. We have also re-refined the crystal structure of CO[bond]myoglobin by a combined quantum chemical and crystallographic refinement. Thereby, we probably obtain the most accurate available structure of the active site of this complex, showing a Fe[bond]C[bond]O angle of 171 degrees, and Fe[bond]C and C[bond]O bond lengths of 170-171 and 116-117 pm. The resulting structures have been used to calculate the strength of the hydrogen bond between the distal histidine residue and O(2) or CO in the protein. This amounts to 31-33 kJ/mol for O(2) and 2-3 kJ/mol for CO. The difference in hydrogen-bond strength is 21-22 kJ/mol when corrected for entropy effects. This is slightly larger than the observed discrimination between O(2) or CO by myoglobin, 17 kJ/mol. We have also estimated the strain of the active site inside the protein. It is 2-4 kJ/mol larger for the O(2) complex than for the CO complex, independent of which crystal structure the calculations are based on. Together, these results clearly show that myoglobin discriminates between O(2) and CO mainly by electrostatic interactions, rather than by steric strain.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0162-0134
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
91
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
101-15
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2002
pubmed:articleTitle
Theoretical study of the discrimination between O(2) and CO by myoglobin.
pubmed:affiliation
Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, S-221 00 Lund, Sweden.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't