Linked Life Data

1312933

Source:http://linkedlifedata.com/resource/pubmed/id/1312933

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1992-4-24
pubmed:abstractText
A c-type monoheme ferricytochrome c550 (9.6 kDa) was isolated from cells of Bacillus halodenitrificans sp.nov., grown anaerobically as a denitrifier. The visible absorption spectrum indicates the presence of a band at 695 nm characteristic of heme-methionine coordination. The midpoint redox potential was determined at several pH values by visible spectroscopy. The redox potential at pH 7.6 is 138 mV. When studied by 1H-NMR spectroscopy as a function of pH, the spectrum shows a pH dependence with pKa values of 6.0 and 11.0. According to these pKa values, three forms designated as I, II and III can be attributed to cytochrome c550. The first pKa is probably associated with protonation of the propionate groups. The second pKa value introduces a larger effect in the 1H-NMR spectrum and is probably due to the ionisation of the axial histidine. Studies of temperature variation of the 1H-NMR spectra for both the ferrous and ferri forms of the cytochrome were performed. Heme meso protons, the heme methyl groups, the thioether protons, two protons from a propionate and the methylene protons from the axial methionine were identified in the reduced form. The heme methyl resonances of the ferri form were also assigned. EPR spectroscopy was also used to probe the ferric heme environment. A signal at gmax approximately 3.5 at pH 7.5 was observed indicating an almost axial heme environment. At higher pH values the signal at gmax approximately 3.5 converts mainly to a signal at g approximately 2.96. The pKa associated with this change is around 11.3. The N-terminal sequence of this cytochrome was determined and compared with known amino acid sequences of other cytochromes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
204
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1131-9
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
NMR and EPR studies on a monoheme cytochrome c550 isolated from Bacillus halodenitrificans.
pubmed:affiliation
Centro de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Portugal.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, Non-P.H.S.