Linked Life Data

15225055

Source:http://linkedlifedata.com/resource/pubmed/id/15225055

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
26
pubmed:dateCreated
2004-6-30
pubmed:abstractText
An idealized, water-soluble D(2)-symmetric diheme protein is constructed based on a mathematical parametrization of the backbone coordinates of the transmembrane diheme four-helix bundle in cytochrome bc(1). Each heme is coordinated by two His residues from diagonally apposed helices. In the model, the imidazole rings of the His ligands are held in a somewhat unusual perpendicular orientation as found in cytochrome bc(1), which is maintained by a second-shell hydrogen bond to a Thr side chain on a neighboring helix. The resulting peptide is unfolded in the apo state but assembles cooperatively upon binding to heme into a well-folded tetramer. Each tetramer binds two hemes with high affinity at low micromolar concentrations. The equilibrium reduction midpoint potential varies between -76 mV and -124 mV vs SHE in the reducing and oxidizing direction, respectively. The EPR spectrum of the ferric complex indicates the presence of a low-spin species, with a g(max) value of 3.35 comparable to those obtained for hemes b of cytochrome bc(1) (3.79 and 3.44). This provides strong support for the designed perpendicular orientation of the imidazole ligands. Moreover, NMR spectra show that the protein exists in solution in a unique conformation and is amenable to structural studies. This protein may provide a useful scaffold for determining how second-shell ligands affect the redox potential of the heme cofactor.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0002-7863
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
126
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8141-7
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
De novo design of a D2-symmetrical protein that reproduces the diheme four-helix bundle in cytochrome bc1.
pubmed:affiliation
Johnson Research Foundation and Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA. gghirlanda@asu.edu
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.