home > seminars 2010 > Qiu


Prof. XiangYun Qiu

Department of Physics, The George Washington University


October 20, 3:30 PM

Thirkield Hall (Physics), room 103


Electrostatic, hydration, and bending forces in compact DNA assemblies


Our interest in nucleic acids has transcended their role as the carrier of genetic information. Nucleic acids are being pursued as promising therapeutic agents, versatile bioengineering materials, and model biophysical systems. Our research is inspired by the prevalence of compact DNA/RNA assemblies in biology and bioengineering. Observing DNA as one of the most highly charged biomolecules, we aimed to elucidate the role of ubiquitous cations in packaging like-charged DNA helices. We have combined small angle x-ray scattering methods and physical theories to quantify how the interaction between DNA helices is modulated by cations of various valences. While the cation-modulated DNA-DNA repulsion and attraction are driven by electrostatics, hydration forces due to water restructuring must be taken into account to explain experimental data. I will lastly touch upon two new developments in our lab. First is the system of DNA triplex with divalent cations exhibiting surprising condensation. The other is the liquid crystalline genomic DNA inside bacteriophage lambda where we have experimentally quantified the rather large DNA pressure (~50 atmospheres) and established the role of DNA bending force.


Refreshments will be served at 3:15 pm