The coarse-grained Martini force field is widely used in biomolecular simulations. Here, we present the refined model, Martini 3 (http://cgmartini.nl), with an improved interaction balance, new bead types, and expanded ability to include specific interactions representing, e.g. hydrogen bonding and electronic polarizability. The new model allows more accurate predictions of molecular packing and interactions in general, which is exemplified with a vast and diverse set of applications, ranging from oil/water partitioning and miscibility data to complex molecular systems, involving protein-protein and protein-lipid interactions and material science applications as ionic liquids and aedamers.
Molecular dynamics simulations play an increasingly important role in the rational design of (nano)-materials and in the study of biomacromolecules. However, generating input files and realistic starting coordinates for these simulations is a major bottleneck, especially for high throughput protocols and for complex multi-component systems. To eliminate this bottleneck, we present the polyply software suite that provides 1) a multi-scale graph matching algorithm designed to generate parameters quickly and for arbitrarily complex polymeric topologies, and 2) a generic multi-scale random walk protocol capable of setting up complex systems efficiently and independent of the target force-field or model resolution. We benchmark quality and performance of the approach by creating realistic coordinates for polymer melt simulations, single-stranded as well as circular single-stranded DNA. We further demonstrate the power of our approach by setting up a microphase-separated block copolymer system, and by generating a liquid-liquid phase separated system inside a lipid vesicle.
Self-assembly features
prominently in fields ranging from materials
science to biophysical chemistry. Assembly pathways, often passing
through transient intermediates, can control the outcome of assembly
processes. Yet, the mechanisms of self-assembly remain largely obscure
due to a lack of experimental tools for probing these pathways at
the molecular level. Here, the self-assembly of self-replicators into
fibers is visualized in real-time by high-speed atomic force microscopy
(HS-AFM). Fiber growth requires the conversion of precursor molecules
into six-membered macrocycles, which constitute the fibers. HS-AFM
experiments, supported by molecular dynamics simulations, revealed
that aggregates of precursor molecules accumulate at the sides of
the fibers, which then diffuse to the fiber ends where growth takes
place. This mechanism of precursor reservoir formation, followed by
one-dimensional diffusion, which guides the precursor molecules to
the sites of growth, reduces the entropic penalty associated with
colocalizing precursors and growth sites and constitutes a new mechanism
for supramolecular polymerization.
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