Mixtures of ideal polymers with hard spheres whose diameters are smaller than the radius of gyration of the polymer, exhibit extensive immiscibility. The interfacial tension between demixed phases of these mixtures is estimated, as is the barrier to nucleation. The barrier is found to scale linearly with the radius of the polymer, causing it to become large for large polymers. Thus for large po...

Monomer chromatin particles containing 140 base pairs of DNA and eight histone molecules have been studied by neutron scattering. From measurements in various H2O/D2O mixtures, radii of gyration and the average scattering density of the particle were determined. The radius of gyration under conditions when scattering from the DNA dominates is 50A, and when scattering from the protein dominates,...

Molecular dynamics simulations are used to probe the properties of non-native states of the protein human alpha-lactalbumin (human alpha-LA) with a detailed atomistic model in an implicit aqueous solvent environment. To sample the conformational space, a biasing force is introduced that increases the radius of gyration relative to the native state and generates a large number of low-energy conf...

A new simulation strategy based on a stochastic process has been developed and tested to study the structural properties of the unfolded state of proteins at the atomistic level. The procedure combines a generation algorithm to produce representative uncorrelated atomistic microstructures and an original relaxation method to minimize repulsive non-bonded interactions. Using this methodology, a ...

Small-angle x-ray scattering was used to investigate structural changes upon binding of individual substrates or a transition state analog complex (TSAC; Mg-ADP, creatine, and KNO3) to creatine kinase (CK) isoenzymes (dimeric muscle-type (M)-CK and octameric mitochondrial (Mi)-CK) and monomeric arginine kinase (AK). Considerable changes in the shape and the size of the molecules occurred upon b...

Recent simulations have indicated that the thermodynamic properties and the glassy dynamics of polymer melts are strongly influenced by the average molecular shape, as quantified by the radius of gyration tensor of the polymer molecules, and that the average molecular shape can be tuned by varying the molecular topology (e.g., ring, star, linear chain, etc.). In the present work, we investigate...

Ribonucleic acids are highly conserved essential parts of cellular life. RNA function is determined to a large extent by its hydrodynamic behaviour. The presented study proposes a strategy to predict the hydrodynamic behaviour of RNA single strands on the basis of the polymer size. By atom-level shell-modelling of high-resolution structures, hydrodynamic radius and diffusion coefficient of evol...

The tobacco mosaic virus is used as a model molecular assembly to illustrate the basic potentialities of light scattering techniques (both static and dynamic) to undergraduates. The work has two objectives: a pedagogic one (introducing light scattering to undergraduate students) and a scientific one (stabilization of the virus molecular assembly structure by the nucleic acid). Students are firs...