Linked Life Data

1847080

Source:http://linkedlifedata.com/resource/pubmed/id/1847080

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
7
pubmed:dateCreated
1991-3-21
pubmed:abstractText
The reaction of ferric cytochrome c peroxidase (CcP) from Saccharomyces cerevisiae with peroxide produces compound I, characterized by both an oxyferryl iron center and a protein-based free radical. The electron paramagnetic resonance (EPR) signal of the CcP compound I radical can be resolved into a broad majority component which accounts for approximately 90% of the spin intensity and a narrow minority component which accounts for approximately 10% of the integrated spin intensity [Hori, H., & Yonetani, T. (1985) J. Biol. Chem. 260, 3549-3555]. It was shown previously that the broad component of the compound I radical signal is eliminated by mutation of Trp-191 to Phe [Scholes, C. P., Liu, Y., Fishel, L. F., Farnum, M. F., Mauro, J. M., & Kraut, J. (1989) Isr. J. Chem. 29, 85-92]. The present work probed the effect of mutations in the vicinity of this residue by EPR and electron-nuclear double resonance (ENDOR). These mutations were obtained from a plasmid-encoded form of S. cerevisiae expressed in Escherichia coli [Fishel, L. A., Villafranca, J. E., Mauro, J. M., & Kraut, J. (1987) Biochemistry 26, 351-360]. The EPR line shape and ENDOR signals of the compound I radical were perturbed only by mutations that alter Trp-191 or residues in its immediate vicinity: namely, Met-230 and Met-231, which have sulfur atoms within 4 A of the indole ring, and Asp-235, which forms a hydrogen bond with the indole nitrogen of Trp-191. Mutations of other potential oxidizable sites (tryptophan, tyrosine, methionine, and cysteine) did not alter the EPR line shapes of the compound I radical, although the integrated spin intensities were weaker in some of these mutants. Mutations at Met-230 and/or -231 perturbed the EPR line shapes of the compound I radical signal but did not eliminate it. ENDOR of these two methionine mutants showed alteration to the hyperfine couplings of several strongly coupled protons, which are characteristic of the majority compound I radical electronic structure, and a change in weaker hyperfine couplings, which suggests a different orientation of the radical with respect to its surroundings in the presence of these methionine mutations. Besides the Trp-191----Phe mutation, only the Asp-235----Asn mutation eliminated the broad component of the compound I signal. Loss of the broad compound I EPR signal coincides with both the loss of the Asp----Trp-191 hydrogen-bonding interaction and alteration of the position of the indole ring of Trp-191.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1986-96
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Compound I radical in site-directed mutants of cytochrome c peroxidase as probed by electron paramagnetic resonance and electron-nuclear double resonance.
pubmed:affiliation
Department of Chemistry, University of California, San Diego, La Jolla 92093.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't