Linked Life Data

16605245

Source:http://linkedlifedata.com/resource/pubmed/id/16605245

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
2006-4-11
pubmed:abstractText
Crystal structures and mass spectrometric analyses of catalase-peroxidases (KatGs) from different organisms revealed the existence of a peculiar distal Met-Tyr-Trp cross-link. The adduct appears to be important for the catalase but not the peroxidase activity of bifunctional KatG. To examine the effect of the adduct on enzyme redox properties and functions, we have determined the thermodynamics of ferric reduction for wild-type KatG and KatG(Y249F), whose tyrosine-to-phenylalanine mutation prevents cross-link formation. At 25 degrees C and pH 7.0, the reduction potential of wild-type KatG is found to be -226 +/- 10 mV, remarkably lower than the published literature values. The reduction potential of KatG(Y249F) is very similar (-222 +/- 10 mV), but variable temperature experiments revealed compensatory differences in reduction enthalpies and entropies. In both proteins, the oxidized state is enthalpically stabilized over the reduced state, but entropy is lost on reduction, which is in strong contrast to horseradish peroxidase, which also features a much more pronounced enthalpic stabilization of the ferriheme. With both proteins, the midpoint potential increased linearly with decreasing pH. We discuss whether the observed redox thermodynamics reflects the differences in structure and function between bifunctional KatG and monofunctional peroxidases.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
18
pubmed:volume
45
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4768-74
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2006
pubmed:articleTitle
Redox thermodynamics of the ferric-ferrous couple of wild-type synechocystis KatG and KatG(Y249F).
pubmed:affiliation
Department of Chemistry, University of Modena and Reggio Emilia, via Campi 183, 41100 Modena, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't