Linked Life Data

8547270

Source:http://linkedlifedata.com/resource/pubmed/id/8547270

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1996-2-22
pubmed:abstractText
The two distinct domains of flavocytochrome b2 (L-lactate:cytochrome c oxidoreductase, EC 1.1.2.3) are connected by a typical hinge peptide. To probe the importance of the structural integrity of the hinge region for efficient intraprotein electron transfer, three mutant enzymes have been constructed: H delta 3 [Sharp, R. E., White, P., Chapman, S. K., & Reid, G. A. (1994) Biochemistry 33, 5115-5120], H delta 6, and H delta 9 in which three, six, and nine amino acids, respectively, were deleted from the hinge region. Intraprotein electron transfer was investigated by steady-state and stopped-flow kinetic analyses. All three hinge-deletion enzymes remained good L-lactate dehydrogenases, as was evident from steady-state experiments with ferricyanide as the electron acceptor and from stopped-flow experiments monitoring flavin reduction. The global effect of these deletions is to lower the enzyme's effectiveness as a cytochrome c reductase. This property of H delta 6 and H delta 9 flavocytochromes b2 is manifested at the first interdomain electron-transfer step (fully reduced FMN-->heme electron transfer), where the rate of heme reduction is the same within experimental error as the steady-state rate of cytochrome c reduction. Thus, interdomain electron transfer is rate limiting in the case of these two hinge-deletion enzymes compared to the wild-type enzyme, where alpha H abstraction from C-2 of L-lactate still contributes substantially to rate limitation. The situation for H delta 3 is more complicated, with more than one interdomain electron-transfer step being affected. Kinetic data, along with the measured deuterium kinetic isotope effects, are discussed in the context of the flavocytochrome b2 catalytic cycle and show that complete structural integrity within the hinge region is essential for efficient interdomain communication.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
23
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
891-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Deletions in the interdomain hinge region of flavocytochrome b2: effects on intraprotein electron transfer.
pubmed:affiliation
Institute of Cell and Molecular Biology, Edinburgh Centre for Molecular Recognition, University of Edinburgh, Scotland.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't