유지중 교수

Atomic-scale modeling of compacted nucleic acids has the ability to reveal the inner workings of spectacular biomolecular machines, yet the outcome of such modeling efforts sensitively depends on the accuracy of the underlying computational models. Our molecular dynamics simulations of an array of 64 parallel duplex DNA revealed considerable artifacts of cation–DNA phosphate interactions in CHARMM and AMBER parameter sets: both the DNA arrangement and the pressure inside the DNA arrays were foun

In contrast to ordinary polymers, the vast majority of biological macromolecules adopt highly ordered three-dimensional structures that define their functions. The key to folding of a biopolymer into a unique 3D structure or to an assembly of several biopolymers into a functional unit is a delicate balance between the attractive and repulsive forces that also makes such self-assembly reversible under physiological conditions. The all-atom molecular dynamics (MD) method has emerged as a powerful

Over the past decades, molecular dynamics (MD) simulations of biomolecules have become a mainstream biophysics technique. As the length and time scales amenable to the MD method increase, shortcomings of the empirical force fields, which have been developed and validated using relatively short simulations of small molecules, become apparent. One common artifact is aggregation of water-soluble biomolecules driven by artificially strong charge-charge interactions. Here, we report a systematic atom

The DNA origami method permits folding of long single-stranded DNA into complex 3D structures with subnanometer precision. Transmission electron microscopy, atomic force microscopy, and recently cryo-EM tomography have been used to characterize the properties of such DNA origami objects, however their microscopic structures and dynamics have remained unknown. Here, we report the results of all-atom molecular dynamics simulations that characterized the structural and mechanical properties of DNA

The concept of "ion atmosphere" is prevalent in both theoretical and experimental studies of nucleic acid systems, yet the spatial arrangement and the composition of ions in the ion atmosphere remain elusive, in particular when several ionic species (e.g., Na(+), K(+), and Mg(2+)) compete to neutralize the charge of a nucleic acid polyanion. Complementing the experimental study of Bai and co-workers (J. Am. Chem. Soc.2007, 129, 14981), here we characterize ion atmosphere around double-stranded D

Spontaneous assembly of DNA molecules into compact structures is ubiquitous in biological systems. Experiment has shown that polycations can turn electrostatic self-repulsion of DNA into attraction, yet the physical mechanism of DNA condensation has remained elusive. Here, we report the results of atomistic molecular dynamics simulations that elucidated the microscopic structure of dense DNA assemblies and the physics of interactions that makes such assemblies possible. Reproducing the setup of

DNA self-assembly has emerged as a new paradigm for design of biomimetic membrane channels. Several experimental groups have already demonstrated assembly and insertion of DNA channels into lipid bilayer membranes; however, the structure of the channels and their conductance mechanism have remained undetermined. Here, we report the results of molecular dynamics simulations that characterized the biophysical properties of the DNA membrane channels with atomic precision. We show that, while overal

Although proteins mediate highly ordered DNA organization in vivo, theoretical studies suggest that homologous DNA duplexes can preferentially associate with one another even in the absence of proteins. Here we combine molecular dynamics simulations with single-molecule fluorescence resonance energy transfer experiments to examine the interactions between duplex DNA in the presence of spermine, a biological polycation. We find that AT-rich DNA duplexes associate more strongly than GC-rich duplex

Calcium ions (Ca(2+) ) play key roles in various fundamental biological processes such as cell signaling and brain function. Molecular dynamics (MD) simulations have been used to study such interactions, however, the accuracy of the Ca(2+) models provided by the standard MD force fields has not been rigorously tested. Here, we assess the performance of the Ca(2+) models from the most popular classical force fields AMBER and CHARMM by computing the osmotic pressure of model compounds and the free

Recent advances in computational technology have enabled brute-force molecular dynamics (MD) simulations of protein folding using physics-based molecular force fields. The extensive sampling of protein conformations afforded by such simulations revealed, however, considerable compaction of the protein conformations in the unfolded state, which is inconsistent with experiment. Here, we show that a set of surgical corrections to nonbonded interactions between amine nitrogen-carboxylate oxygen and

Eukaryotic genome and methylome encode DNA fragments' propensity to form nucleosome particles. Although the mechanical properties of DNA possibly orchestrate such encoding, the definite link between 'omics' and DNA energetics has remained elusive. Here, we bridge the divide by examining the sequence-dependent energetics of highly bent DNA. Molecular dynamics simulations of 42 intact DNA minicircles reveal that each DNA minicircle undergoes inside-out conformational transitions with the most like