Linked Life Data

1645996

Source:http://linkedlifedata.com/resource/pubmed/id/1645996

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
23
pubmed:dateCreated
1991-7-18
pubmed:abstractText
Previous structural studies on the complexes of the chromomycin (CHR) dimer with duplexes of d(A1-A2-G3-G4-C5-C6-T7-T8) and of d(A1-G2-G3-A4-T5-C6-C7-T8) in solution [one Mg(II) and two drugs per duplex] are extended to hydrogen exchange measurements. Exchange of the OH8 proton of chromomycin, measured by real time proton-deuterium exchange, is very slow and requires dissociation of the complex, whose lifetime is thus determined. The lifetimes and apparent dissociation constants of base pairs are deduced from the catalysis of imino proton exchange by ammonia. The four central base pairs, which interact with the CHR chromophores in the minor groove (Gao & Patel, 1990), may open within the complex, but the opening rate is less than in the free duplex by one to two orders of magnitude. The activation energy for base-pair opening and the differences between the lifetimes of adjacent pairs suggest that single base-pair opening is the predominant imino proton exchange pathway in all cases. In the symmetrical complex of chromomycin with the first duplex, the lifetimes of the central base pairs (G3.C6 and G4.C5) are in the same range (52 and 29 ms, respectively, at 38 degrees C). In the asymmetrical complex formed with the second duplex, the base-pair lifetimes in the G2-G3-A4-T5 segment that interacts with the chromophore moiety are strongly increased. That of G3.C6 is particularly long. Above 50 degrees C, exchange of the G3 imino proton is opening limited.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5653-61
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Proton exchange and internal motions in two chromomycin dimer-DNA oligomer complexes.
pubmed:affiliation
Groupe de Biophysique, Ecole Polytechnique, Palaiseau, France.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't