RESUMO
We present molecular-level simulations of dendrimer/DNA complexes in the presence of a model cell membrane. We determine the required conditions for the complex to arrive intact at the membrane, and the lifetime of the complex as it resides attached to the membrane. Our simulations directly pertain to critical issues arising in emerging gene delivery therapeutic applications, where a molecular carrier is required to deliver DNA segments to the interior of living cells.
Assuntos
Membrana Celular/química , Dendrímeros/química , Vetores Genéticos/síntese química , Simulação por Computador , DNA/química , Vetores Genéticos/química , Modelos Moleculares , ProbabilidadeRESUMO
A study of the micromechanical unzipping of DNA in the framework of the Peyrard-Bishop-Dauxois model is presented. We introduce a Monte Carlo technique that allows accurate determination of the dependence of the unzipping forces on unzipping speed and temperature. Our findings agree quantitatively with experimental results for homogeneous DNA, and for lamda-phage DNA we reproduce the recently obtained experimental force-temperature phase diagram. Finally, we argue that there may be fundamental differences between in vivo and in vitro DNA unzipping.
Assuntos
Pareamento de Bases , DNA Viral/química , DNA/química , Modelos Químicos , Conformação de Ácido Nucleico , Bacteriófago lambda/química , Desnaturação de Ácido NucleicoRESUMO
Using a well established model, we systematically analyze fundamental limitations on the viability of using mechanical unzipping of DNA as a fast and inexpensive sequencing method. Standard unzipping techniques, where double-stranded DNA is unzipped through the application of a force at one end of the molecule, are shown to be inadequate. Emerging techniques that unzip DNA by local force application are more promising, and we establish the necessary experimental requirements that must be met for these techniques to succeed as single molecule sequencing tools.
Assuntos
Análise de Sequência de DNA , Microscopia de Força Atômica , Modelos Químicos , Análise de Sequência de DNA/instrumentação , Análise de Sequência de DNA/métodosRESUMO
The onset of intermediate states (denaturation bubbles) and their role during the melting transition of DNA are studied using the Peyrard-Bishop-Dauxois model by Monte Carlo simulations with no adjustable parameters. Comparison is made with previously published experimental results finding excellent agreement. Melting curves, critical DNA segment length for stability of bubbles, and the possibility of a two-state transition are studied.
