Linked Life Data

21153851

Source:http://linkedlifedata.com/resource/pubmed/id/21153851

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2011-2-2
pubmed:databankReference
pubmed:abstractText
Homoprotocatechuate 2,3-dioxygenase from Brevibacterium fuscum (HPCD) has an Fe(II) center in its active site that can be replaced with Mn(II) or Co(II). Whereas Mn-HPCD exhibits steady-state kinetic parameters comparable to those of Fe-HPCD, Co-HPCD behaves somewhat differently, exhibiting significantly higher [Formula: see text] and k (cat). The high activity of Co-HPCD is surprising, given that cobalt has the highest standard M(III/II) redox potential of the three metals. Comparison of the X-ray crystal structures of the resting and substrate-bound forms of Fe-HPCD, Mn-HPCD, and Co-HPCD shows that metal substitution has no effect on the local ligand environment, the conformational integrity of the active site, or the overall protein structure, suggesting that the protein structure does not differentially tune the potential of the metal center. Analysis of the steady-state kinetics of Co-HPCD suggests that the Co(II) center alters the relative rate constants for the interconversion of intermediates in the catalytic cycle but still allows the dioxygenase reaction to proceed efficiently. When compared with the kinetic data for Fe-HPCD and Mn-HPCD, these results show that dioxygenase catalysis can proceed at high rates over a wide range of metal redox potentials. This is consistent with the proposed mechanism in which the metal mediates electron transfer between the catechol substrate and O(2) to form the postulated [M(II)(semiquinone)superoxo] reactive species. These kinetic differences and the spectroscopic properties of Co-HPCD provide new tools with which to explore the unique O(2) activation mechanism associated with the extradiol dioxygenase family.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1432-1327
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
16
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
341-55
pubmed:dateRevised
2011-10-13
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
A hyperactive cobalt-substituted extradiol-cleaving catechol dioxygenase.
pubmed:affiliation
Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street, Minneapolis, MN 55455, USA.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural