Linked Life Data

2551370

Source:http://linkedlifedata.com/resource/pubmed/id/2551370

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
15
pubmed:dateCreated
1989-11-22
pubmed:abstractText
The effect of ionic strength on the rate constant for electron transfer has been used to determine the magnitude and charge sign of the net electrostatic potential which exists in close proximity to the sites of electron transfer on various c-type cytochromes. The negatively charged ferricyanide ion preferentially reacts at the positively charged exposed heme edge region on the front side of horse cytochrome c and Paracoccus cytochrome c2. In contrast, at low ionic strength, the positively charged cobalt phenanthroline ion interacts with the negatively charged back side of cytochrome c2, and at high ionic strength at a positively charged site on the front side of the cytochrome. With horse cytochrome c, over the ionic strength range studied, cobalt phenanthroline reacts only at a positively charged site which is probably not at the heme edge. These inorganic oxidants do not react at the relatively uncharged exposed heme edge sites on Azotobacter cytochrome c5 and Pseudomonas cytochrome c-551, but rather at a negatively charged site which is away from the heme edge. The results demonstrate that at least two electron-transferring sites on a single cytochrome can be functional, depending on the redox reactant used and the ionic strength. Electrostatic interactions between charge distributions on the cytochrome surface and the other reactant, or interactions involving uncharged regions on the protein(s), are critical in determining the preferred sites of electron transfer and reaction rate constants. When unfavorable electrostatic effects occur at a site near the redox center, less optimal sites at a greater distance can become kinetically important.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
28
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6318-22
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1989
pubmed:articleTitle
Redox protein electron-transfer mechanisms: electrostatic interactions as a determinant of reaction site in c-type cytochromes.
pubmed:affiliation
Department of Biochemistry, University of Arizona, Tucson 85721.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.