Linked Life Data

8260499

Source:http://linkedlifedata.com/resource/pubmed/id/8260499

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
51
pubmed:dateCreated
1994-1-25
pubmed:abstractText
The binding of ferrous and ferric hemes and manganese(II)- and manganese(III)-substituted hemes to heme oxygenase has been investigated by optical absorption, resonance Raman, and EPR spectroscopy. The results are consistent with the presence of a six-coordinate heme moiety ligated to an essential histidine ligand and a water molecule. The latter ionizes with a pKa approximately 8.0 to give a mixture of high-spin and low-spin six-coordinate hydroxo adducts. Addition of excess cyanide converts the heme to a hexacoordinate low-spin species. The resonance Raman spectrum of the ferrous heme-heme oxygenase complex and that of the Mn(II)protoporphyrin-heme oxygenase complex shows bands at 216 and 212 cm-1, respectively, that are assigned to the metal-histidine stretching mode. The EPR spectrum of the oxidized heme-heme oxygenase complex has a strongly axial signal with g parallel of approximately 6 and g perpendicular approximately 2. 14NO and 15NO adducts of ferrous heme-heme oxygenase exhibit EPR hyperfine splittings of approximately 20 and approximately 25 Gauss, respectively. In addition, both nitrosyl complexes show additional superhyperfine splittings of approximately 7 Gauss from spin-spin interaction with the proximal histidine nitrogen. The heme environment in the heme-heme oxygenase enzyme-substrate complex has spectroscopic properties similar to those of the heme in myoglobin. Hence, there is neither a strongly electron-donating fifth (proximal) ligand nor an electron-withdrawing network on the distal side of the heme moiety comparable to that for cytochromes P-450 and peroxidases. This observation has profound implications about the nature of the oxygen-activating process in the heme-->biliverdin reaction that are discussed in this paper.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
32
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14151-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Resonance Raman and EPR spectroscopic studies on heme-heme oxygenase complexes.
pubmed:affiliation
Department of Chemistry, Biochemistry, and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland 97291-1000.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.