Open AccessDissociation Kinetics of Actinomycin D from Individual GpC Sites in DNA
Author(s) -
Fletcher Michael C.,
Fox Keith R.
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0164n.x
Subject(s) - footprinting , dna , dna footprinting , kinetics , dissociation (chemistry) , chemistry , deoxyribonuclease i , microbiology and biotechnology , binding site , biophysics , biology , stereochemistry , biochemistry , dna binding protein , gene , base sequence , transcription factor , physics , quantum mechanics
We have examined the kinetics of dissociation of actinomycin from GpC sites in several DNA fragments containing synthetic DNA inserts, by a variation of the footprinting technique. Complexes of the ligand with radiolabelled DNA fragments were dissociated by adding a large excess of unlabelled calf thymus DNA. Samples were removed from this mixture at subsequent time intervals and subjected to DNase I footprinting. The rate of disappearance of the footprints varied considerably between the GpC sites located in different sequence environments. Actinomycin dissociates more slowly from GpC sites flanked by (AT) n than A n · T n . Within regions of alternating AT, TGCA represents a better binding site than AGCT, and CGCA is a better binding site than GGCA. GpC sites flanked by (AC) n · (GT) n present good binding sites; in this context, dissociation from CGCG is faster than from TGCA.