The Trimeric Major Capsid Protein of Mavirus is stabilized by its Interlocked N-termini Enabling Core Flexibility for Capsid Assembly.

Icosahedral viral capsids assemble with high fidelity from a large number of identical buildings blocks. The mechanisms that enable individual capsid proteins to form stable oligomeric units (capsomers) while affording structural adaptability required for further assembly into capsids are mostly unknown. Understanding these mechanisms requires knowledge of the capsomers' dynamics, especially for viruses where no additional helper proteins are needed during capsid assembly like for the Mavirus virophage that despite its complexity (triangulation number T = 27) can assemble from its major capsid protein (MCP) alone.

Probing the Chemistry of Adhesion between a 316L Substrate and Spin-on-Glass Coating.

Hydrogen silsesquioxane ([HSiO] )-based "spin-on-glass" has been deposited on a 316L substrate and cured in Ar/H gas atmosphere at 600 °C to form a continuous surface coating with submicrometer thickness. The coating functionality depends primarily on the adhesion to the substrate, which is largely affected by the chemical interaction at the interface between the coating and the substrate. We have investigated this interface by transmission electron microscopy and electron energy loss spectroscopy.

Black metal thin films by deposition on dielectric antireflective moth-eye nanostructures.

Although metals are commonly shiny and highly reflective, we here show that thin metal films appear black when deposited on a dielectric with antireflective moth-eye nanostructures. The nanostructures were tapered and close-packed, with heights in the range 300-600 nm, and a lateral, spatial frequency in the range 5-7 μm(-1). A reflectance in the visible spectrum as low as 6%, and an absorbance of 90% was observed for an Al film of 100 nm thickness.

Plasmonic metasurfaces for coloration of plastic consumer products.

We present reflective plasmonic colors based on the concept of localized surface plasmon resonances (LSPR) for plastic consumer products. In particular, we bridge the widely existing technological gap between clean-room fabricated plasmonic metasurfaces and the practical call for large-area structurally colored plastic surfaces robust to daily life handling. We utilize the hybridization between LSPR modes in aluminum nanodisks and nanoholes to design and fabricate bright angle-insensitive colors that may be tuned across the entire visible spectrum.

Synthetic crowding agent dextran causes excluded volume interactions exclusively to tracer protein apoazurin.

To understand protein biophysics in crowded cellular environments, researchers often use synthetic polymers as 'crowding agents' in vitro. The idea is that these agents will occupy space and reproduce the in vivo scenario in terms of excluded volume. However, recent work has challenged this concept and pointed out that attractive interactions between protein and crowding agent will provide an enthalpic contribution to the overall effect on protein thermodynamics.

Enhancing the chroma of pigmented polymers using antireflective surface structures.

In this paper we investigate how the color of a pigmented polymer is affected by reduction of the reflectance at the air-polymer interface. Both theoretical and experimental investigations show modified diffuse-direct reflectance spectra when the reflectance of the surface is lowered. Specifically it is found that the color change is manifested as an increase in chroma, leading to a clearer color experience.

Quantification of excluded volume effects on the folding landscape of Pseudomonas aeruginosa apoazurin in vitro.

Proteins fold and function inside cells that are crowded with macromolecules. Here, we address the role of the resulting excluded volume effects by in vitro spectroscopic studies of Pseudomonas aeruginosa apoazurin stability (thermal and chemical perturbations) and folding kinetics (chemical perturbation) as a function of increasing levels of crowding agents dextran (sizes 20, 40, and 70 kDa) and Ficoll 70. We find that excluded volume theory derived by Minton quantitatively captures the experimental effects when crowding agents are modeled as arrays of rods.

Effects of macromolecular crowding agents on protein folding in vitro and in silico.

Proteins fold and function inside cells which are environments very different from that of dilute buffer solutions most often used in traditional experiments. The crowded milieu results in excluded-volume effects, increased bulk viscosity and amplified chances for inter-molecular interactions. These environmental factors have not been accounted for in most mechanistic studies of protein folding executed during the last decades.

Effects of macromolecular crowding on burst phase kinetics of cytochrome c folding.

Excluded volume and viscosity effects of crowding agents that mimic crowded conditions in vivo on "classical" burst phase folding kinetics of cytochrome c are assessed in vitro. Upon electron transfer-triggered folding of reduced cytochrome c, far-UV time-resolved circular dichroism (TRCD) is used to monitor folding under different conditions. Earlier work has shown that folding of reduced cytochrome c from the guanidinium hydrochloride-induced unfolded ensemble in dilute phosphate buffer involves kinetic partitioning: one fraction of molecules folds rapidly, on a time scale identical to that of reduction, while the remaining population folds more slowly.

Color effects from scattering on random surface structures in dielectrics.

We show that cheap large area color filters, based on surface scattering, can be fabricated in dielectric materials by replication of random structures in silicon. The specular transmittance of three different types of structures, corresponding to three different colors, have been characterized. The angle resolved scattering has been measured and compared to predictions based on the measured surface topography and by the use of non-paraxial scalar diffraction theory.

Comparison of chemical and thermal protein denaturation by combination of computational and experimental approaches. II.

Chemical and thermal denaturation methods have been widely used to investigate folding processes of proteins in vitro. However, a molecular understanding of the relationship between these two perturbation methods is lacking. Here, we combined computational and experimental approaches to investigate denaturing effects on three structurally different proteins.

Extraordinary μs-ms backbone dynamics in Arabidopsis thaliana peroxiredoxin Q.

Peroxiredoxin Q (PrxQ) isolated from Arabidopsis thaliana belongs to a family of redox enzymes called peroxiredoxins, which are thioredoxin- or glutaredoxin-dependent peroxidases acting to reduce peroxides and in particular hydrogen peroxide. PrxQ cycles between an active reduced state and an inactive oxidized state during its catalytic cycle. The catalytic mechanism involves a nucleophilic attack of the catalytic cysteine on hydrogen peroxide to generate a sulfonic acid intermediate with a concerted release of a water molecule.

Macromolecular crowding tunes folding landscape of parallel α/β protein, apoflavodoxin.

Proteins normally fold in crowded cellular environments. Here we use a set of Desulfovibrio desulfuricans apoflavodoxin variants to assess--with residue-specific resolution--how apoflavodoxin's folding landscape is tuned by macromolecular crowding. We find that, under crowded conditions, initial topological frustration is reduced, subsequent folding requires less ordering in the transition state, and β-strand 1 becomes more important in guiding the process.

Factors defining effects of macromolecular crowding on protein stability: an in vitro/in silico case study using cytochrome c.

Previous experiments with two single-domain proteins showed that macromolecular crowding can stabilize dramatically toward heat perturbation and modulate native-state structure and shape. To assess the generality of this, we here tested the effects of the synthetic crowding agents on cytochrome c, a small single-domain protein. Using far-UV circular dichroism (CD), we discovered that there is no effect on cytochrome c's secondary structure upon addition of Ficoll or dextran (0-400 mg/mL, pH 7).