Structural polymorphism of DNA-dendrimer complexes.
DNA condensation in vivo relies on electrostatic complexation with small cations or large histones. We report a synchrotron x-ray study of the phase behavior of DNA complexed with synthetic cationic dendrimers of intermediate size and charge. We encounter unexpected structural transitions between columnar mesophases with in-plane square and hexagonal symmetries, as well as liquidlike disorder. The isoelectric point is a locus of structural instability. A simple model is proposed based on competing long-range electrostatic interactions and short-range entropic adhesion by counterion release.
Evans
Heather M
HM
Materials Department, Physics Department, and Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106, USA.
Ahmad
A
A
Ewert
K
K
Pfohl
T
T
Martin-Herranz
A
A
Bruinsma
R F
RF
Safinya
C R
CR
D002412:Cations / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D006657:Histones / Q000737:chemistry; D008954:Models, Biological; D008958:Models, Molecular; D011126:Polypropylenes / Q000737:chemistry*; D055672:Static Electricity
D002412:Cations; D006657:Histones; D011126:Polypropylenes; D004247:DNA