Large electrostatic differences in the binding thermodynamics of a cationic peptide to oligomeric and polymeric DNA.
Results presented here demonstrate that the thermodynamics of oligocation binding to polymeric and oligomeric DNA are not equivalent because of long-range electrostatic effects. At physiological cation concentrations (0.1-0.3 M) the binding of an oligolysine octacation KWK6-NH2 (+8 charge) to single-stranded poly(dT) is much stronger per site and significantly more salt concentration dependent than the binding of the same ligand to an oligonucleotide, dT(pdT)10 (-10 charge). These large differences are consistent with Poisson-Boltzmann calculations for a model that characterizes the charge distributions with key preaveraged structural parameters. Therefore, both the experimental and the theoretical results presented here show that the polyelectrolyte character of a polymeric nucleic acid makes a large contribution to both the magnitude and the salt concentration dependence of its binding interactions with simple oligocationic ligands.
Zhang
W
W
Department of Chemistry, University of Wisconsin, Madison 53706, USA.
Bond
J P
JP
Anderson
C F
CF
Lohman
T M
TM
Record
M T
MT
D002412:Cations / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D011071:Poly T / Q000737:chemistry; D011485:Protein Binding; D012996:Solutions; D013329:Structure-Activity Relationship; D013816:Thermodynamics
D002412:Cations; D008024:Ligands; D009838:Oligodeoxyribonucleotides; D012996:Solutions; D011071:Poly T; D004247:DNA