Unknown

Dataset Information

0

Dissociation of the AT-specific bifunctional intercalator [N-MeCys3,N-MeCys7]TANDEM from TpA sites in DNA.


ABSTRACT: We have examined the dissociation of [N-MeCys3,N-MeCys7]TANDEM, an AT-selective bifunctional intercalator, from TpA sites in mixed-sequence DNAs by a modification of the footprinting technique. Dissociation of complexes between the ligand and radiolabelled DNA fragments was initiated by adding a vast excess of unlabelled calf thymus DNA. Portions of this mixture were subjected to DNAse I footprinting at various times after adding the competitor DNA. Dissociation of the ligand from each site was seen by the time-dependent disappearance of the footprinting pattern. Within a natural DNA fragment (tyrT) the ligand dissociates from TTAT faster than from ATAT. We found that the stability of complexes with isolated TpA steps decreases in the order ATAT > TTAA > TATA. Dissociation from each of these sites is much faster than from longer regions of (AT)n. These results confirm the requirement for A and T base-pairs surrounding the TpA step and suggest that the interaction is strongest with regions of alternating AT, possibly as a result of its unusual structure. The ligand dissociates more slowly from the centre of (AT)n tracts than from the edges, suggesting that variations in dissociation rate arise from sequence-dependent variations in local DNA structure.

SUBMITTER: Fletcher MC 

PROVIDER: S-EPMC1136475 | biostudies-other | 1995 Feb

REPOSITORIES: biostudies-other

Similar Datasets

| S-EPMC1132212 | biostudies-other
| S-EPMC3838791 | biostudies-literature
| S-EPMC5734666 | biostudies-literature
| S-EPMC3811032 | biostudies-other
| S-EPMC9297878 | biostudies-literature
| S-EPMC10711434 | biostudies-literature
| S-EPMC2966942 | biostudies-literature
| S-EPMC9033842 | biostudies-literature
| S-EPMC2655493 | biostudies-literature
| S-EPMC1794346 | biostudies-literature