Linked Life Data

9208175

Source:http://linkedlifedata.com/resource/pubmed/id/9208175

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1997-8-19
pubmed:abstractText
An understanding of the conformational behavior of the stereoisomeric tetrols at the 11,12,13,14-positions of dibenzo[a,l]pyrene (DB[a,l]P) is essential for the spectroscopic identification of DNA adducts derived from the biologically highly active fjord region syn- and anti-DB[a,l]P-11,12-diol 13,14-epoxides. Conformational effects are expected to play an important role in DNA-DB[a,l]P diol epoxide reactivity, base-sequence specificity, and conformation dependent repair. The results of conformational studies on trans-anti-, cis-anti-, and cis-syn-DB[a,l]P tetrol isomers are presented and compared to the results obtained previously for trans-syn-DB[a,l]P tetrol (Carcinogenesis 17, 829-837, 1996). Molecular mechanics, dynamical simulations, and semiempirical calculations of electronic transitions are used to interpret the low-temperature fluorescence spectra and 1H NMR data. Molecular dynamics simulations (in vacuo) identified two conformers (I and II) for each of the tetrol isomers; in all conformations the aromatic ring system is severely distorted. Fluorescence line-narrowing (FLN) spectroscopy identified two distinct conformational species for the trans-anti isomer, one occurring in ethanol and the other occurring in a glycerol/water matrix. The corresponding structures are assigned based on the S1<--S0 transition energies calculated for conformers I and II, respectively. 1H NMR spectroscopy confirmed the structure of conformer I at room temperature. In contrast to trans-syn-DB[a,l]P tetrol (where the major conformation was identified as a boat structure), both conformations of trans-anti-DB[a,l]P tetrol feature a half-chair structure for the cyclohexenyl ring with different orientations of the hydroxyl groups. For cis-anti- and cis-syn-DB[a,l]P tetrols, only a single conformer is detected by FLN spectroscopy. The NMR results for the latter appear to be most consistent with a mixture of two half-chair conformers I and II, while for the cis-anti isomer a flattened, boatlike conformation was observed. The generally good agreement between the NMR coupling constants and those estimated theoretically indicates that these structures should serve as good starting points for spectroscopic or computational studies of DNA adducts derived from DB[a,l]P diol epoxides.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0893-228X
pubmed:author
pubmed:issnType
Print
pubmed:volume
10
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
677-86
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Conformational studies of stereoisomeric tetrols derived from syn- and anti-dibenzo[a,l]pyrene diol epoxides.
pubmed:affiliation
Ames Laboratory-USDOE, Iowa 50011, USA. jankowiak@ameslab.gov
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.