Linked Life Data

7578019

Source:http://linkedlifedata.com/resource/pubmed/id/7578019

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
43
pubmed:dateCreated
1995-12-15
pubmed:abstractText
In cytochrome c, ligation of the heme iron by the methionine-80 sulfur plays a major role in determining the structure and the thermodynamic stability of the protein. In the ferric state, this bond is reversibly broken by moderately acid or alkaline pH's (pK's 2.5 and 9.4, respectively) and by exogenous ligands. NMR studies of horse ferricytochrome c in which the Met-65 and Met-80 methyl groups were chemically enriched with 13C demonstrate that, at 59 degrees C, a temperature at which the protein is still folded, the sulfur-iron bond is already partially broken. This structural change corresponds to the reversible disappearance upon moderate heating of the 695 nm band, characteristic of the sulfur-iron coordination of this protein. The thermal effect results from a shift in the alkaline pK from 9.4 at 25 degrees C to 8.2 at 59 degrees C. The exchange rate from iron-bound to free methionine-80 at 59 degrees C is 1.8 s-1, as measured by saturation transfer experiments. The free and bound methionine-80 epsilon-methyl groups in the 1H spectrum are assigned as (1.87, 2.25) and -21.43, respectively; in the 13C spectrum they are assigned as 15.6 and 12.8, respectively (all these values are in ppm from 3-(trimethylsilyl)propionic-2,2,3,3-d4 acid, sodium salt).
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
31
pubmed:volume
34
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
14209-12
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
The nature of the thermal equilibrium affecting the iron coordination of ferric cytochrome c.
pubmed:affiliation
School of Chemistry, Sackler Faculty of Exact Sciences, Tel Aviv University, Israel.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.