Linked Life Data

1653012

Source:http://linkedlifedata.com/resource/pubmed/id/1653012

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
34
pubmed:dateCreated
1991-10-4
pubmed:abstractText
Solid-state 13C NMR spectra were employed to characterize the protonation state of tyrosine in the light-adapted (bR568) and M states of bacteriorhodopsin (bR). Difference spectra (isotopically labeled bR minus natural-abundance bR) were obtained for [4'-13C]Tyr-labeled bR, regenerated with [14-13C]retinal as an internal marker to identify the photocycle states. The [14-13C]retinal has distinct chemical shifts for bR555, for bR568, and for the M intermediate generated and thermally trapped at pH 10 in the presence of 0.3 M KCl or 0.5 M guanidine. Previous work has demonstrated that tyrosine and tyrosinate are easily distinguished on the basis of the chemical shift of the 4'-13C label and that both NMR signals are detectable in dark-adapted bR, although the tyrosinate signal is only present at pH values greater than 12. In the present work, we show that neither the light-adapted form of bR prepared at pH 7 or 10 nor the M state thermally trapped at -80 degrees C in 0.3 M KCl pH 10, or in 0.5 M guanidine pH 10, shows any detectable tyrosinate. In addition, after the M samples were briefly warmed (approximately 30 s), no tyrosinate was observed. However, small (1-2 ppm) changes in the structure or dispersion in the Tyr peak were observed in the M state phototrapped by either method. These changes were reversible when the sample was warmed, although on a time scale slower than the relaxation of the retinal back to the bR568 conformer.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
8366-71
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Mechanism of proton pumping in bacteriorhodopsin by solid-state NMR: the protonation state of tyrosine in the light-adapted and M states.
pubmed:affiliation
Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, Cambridge 02139.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't