Linked Life Data

7248254

Source:http://linkedlifedata.com/resource/pubmed/id/7248254

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1981-9-25
pubmed:abstractText
Chemically induced dynamic nuclear polarization (CIDNP) is generated when tryptophan (Trp), its derivatives, or Trp-containing peptides react with photoexcited flavins in a 360-MHz NMR spectrometer. In contrast to tyrosine (Tyr), we find that the nuclear polarization of Trp originates in an electron-transfer reaction. By use of a series of Trp derivatives, the unpaired spin-density distribution of the Trp radical cation and the ground-state NMR spectrum of Trp are analyzed in detail. The signs and the relative magnitudes of the proton isotropic hyperfine coupling constants for each position around the indole ring in the radical cation deduced from these measurements are the following: position 3 greater than 2 approximately 4 approximately 6 greater than 1 greater than 5 greater than 7, with positions 1, 2, 3, 4, and 6 positive, 5 negative, and 7 essentially zero. This result is inconsistent with most available calculations of the unpaired spin-density distribution but is compatible with the pattern of electrophilic aromatic substitution. The origin of this discrepancy is discussed in detail. Possible mechanistic complications in the reaction leading to CIDNP are discussed. The laser CIDNP spectra of the Trp-rich peptides gramicidins A and B are presented as examples of the resolution enhancement obtained with this technique.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
20
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2880-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1981
pubmed:articleTitle
Laser chemically induced dynamic nuclear polarization study of the reaction between photoexcited flavins and tryptophan derivatives at 360 MHz.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't