Search

Protein lattices that shift the structure and shape anisotropy in response to environmental cues are closely coupled to potential functionality. However, to design and construct shape‐anisotropic protein arrays from the same building blocks in response to different external stimuli remains challenging. Here, by a combination of the multiple, symmetric interaction sites on the outer surface of protein nanocages and the tunable features of phenylalanine‐phenylalanine interactions, a protein engineering approach is reported to construct a variety of superstructures with shape anisotropy, including 3D cubic, 2D hexagonal layered, and 1D rod‐like crystalline protein nanocage arrays by using one single protein building block. Notably, the assembly of these crystalline protein arrays is reversible, which can be tuned by external stimuli (pH and ionic strength). The anisotropic morphologies of the fabricated macroscopic crystals can be correlated with the Å‐to‐nm scale protein arrangement details by crystallographic elucidation. These results enhance the understanding of the freedom offered by an object's symmetry and inter‐object π−π stacking interactions for protein building blocks to assemble into direction‐ and shape‐anisotropic biomaterials. [ABSTRACT FROM AUTHOR]

Constructing different protein nanostructures by using identical building blocks, while realizing their structural transformation in response to external stimuli, remains a challenge. Here, we fabricated protein nanocages and nanorods by using dimeric TmFtn as a building block and reacting with Mg2+/(α, L -lysine) with polymerization degrees of 9 (PLL9) and 15 (PLL15), respectively. Notably, the reversible shape transformation of these two supramolecular protein architectures with different dimensions can be achievable in response to external stimuli. [ABSTRACT FROM AUTHOR]

Abstract: The storage of large quantities of hydrogen at ambient temperature is a key factor in establishing a hydrogen-based economy. One strategy for hydrogen storage is to exploit the interaction between H2 and a solid material by physisorption of hydrogen on porous materials. However, physisorption materials containing MOF, porous carbons, zeolites, clathrates, and synthesized organic polymers physisorb only about 1 wt% of H2 at ambient temperature. One approach to solving this problem is to prepare new classes of physisorption materials which exhibits a mechanism different from the reported materials in hydrogen storage. Here we report the synthesis of apo cross-linked ferritin supramolecules by disulfide bonds, and their holo form. Unlike non-protein adsorbents, the hydrogen storage capacity of these protein materials increases as a function of temperature over the range of 20–40 °C. The holo supramolecules enable the adsorption of hydrogen up to 3.51 wt% at 40 °C and 40 bar H2. In contrast, non-protein physisorption materials such as activated carbon and nano Fe2O3 marginally adsorb hydrogen, and, as reported, their ability to adsorb hydrogen decreases with increasing temperature under the same experimental condition. These results demonstrate that protein materials have a unique hydrogen storage mechanism which offers new opportunities in exploration of physisorption materials at ambient temperature. [Copyright &y& Elsevier]

Hierarchical assembly of naturally occurring assemblies is accurate and responsible for performing various cellular functions. However, Nature's wisdom in navigating the assembly process to desired protein assemblies by the cooperation of multiple noncovalent interactions has been underexploited for protein superstructures constructions. Owing to the chemical diversity of noncovalent interactions, it should be possible to fabricate protein assemblies with novel properties in high efficiency through the cooperation of different noncovalent interaction. Both charged residues and aromatic residues are introduced on the exterior surface of ferritin centered at their symmetry axes, mixing of complementary variants forms ordered assemblies through the cooperation of two kinds of chemical-diverse noncovalent interactions. The assemblies were further characterized in terms of their assembly behavior, structure, size, assembly kinetics, properties and stabilities. We utilized both electrostatic and π-π stacking interactions between complementary nanocages to cooperatively trigger the self-assembly into predesigned interleaved hetero-superlattices which exhibit high electrolyte stability and thermal stability. The size of the hetero-superlattices can be well controlled with ranges from nanometers to micrometers in solution in response to external stimuli such as pH and salt concentration. The hetero-superlattice may have the potential applications in hybrid bio-templating, light-harvesting and compartmentalized encapsulation. [ABSTRACT FROM AUTHOR]

It is widely believed that high-purity protein is critical to crystallization. Impurities can induce lattice strain, internal stress, and rotation disorder, thus decreasing protein crystallization success rate and crystal quality. However, some studies showed that protein could be crystallized from impure solutions; thus, the effect of impurities on protein crystallization remains unclear. Here, we systemically studied the effect of impurity type and concentration on protein crystallization. Results showed that protein crystallization was different when using different impurities. Protein crystallization could be promoted with a low concentration of impurities and inhibited with a high concentration of impurities, and this inhibition can be weakened by an audible sound. The effect of impurities on protein crystallization can be explained by the phase separation theory. In summary, we suggest that proper impurities might be beneficial to enhance protein crystallization. [ABSTRACT FROM AUTHOR]

Methylmercury (MeHg+) as one of the most potent neurotoxins is mainly accumulated in brain, so in vivo imaging detection of MeHg+ in brain is of crucial importance. Herein, we reported a photoluminescent nanosensor for MeHg+ detection in brain by integrating the bioimaging of gold nanoclusters (Au NCs), the fluorescence of Au NCs quenched by MeHg+, and the brain targeting feature of our recently constructed 16-mer shell-like protein (7A). First, Au NCs with 7A as a biotemplate (7A-Au NCs) by a facile and green method in water are fabricated for the first time, the fluorescence of which (∼650 nm) can be quenched by MeHg+ in a dose-dependent manner in vitro. Second, the as-prepared 7A-Au NCs are not only suitable for bioimaging of BBB endothelial cells, but also are an effective probe for bioimaging MeHg+ detection in a brain-specific manner. These findings open a door for MeHg+ detection in the brain of living subjects. 16-Mer ferritin-like protein templated gold nanoclusters (Au NCs) were fabricated for bioimaging detection of MeHg+ in the brain of living mice by taking advantage of the ability to traverse blood brain barrier, and the bioimaging of Au NCs, the fluorescence of Au NCs quenched by MeHg+. Image 1 • A novel 16-mer ferritin-like protein, 7A, has the ability to pass through blood brain barrier as human H chain ferritin does. • 7A molecules were utilized as biotemplates to fabricate highly fluorescent Au NCs. • 7A biotemplated Au NCs act as biosensors for bioimaging detection of MeHg+ in the brain of living mice. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) hold great promise for numerous applications. However, proteins, carriers of biological functions in living systems, have not yet been fully explored as building blocks for the construction of MOFs. This work presents a strategy for the fabrication of binary MOFs. Considering octahedral ferritin symmetry, four His2 (His–His) motifs were first incorporated into the exterior surface of a ferritin nanocage near each C4 channel, yielding protein linkers with multiple metal‐binding sites (bisH‐SF). Secondly, by adding nickel ions to bisH‐SF solutions triggers the self‐assembly of ferritin nanocages into a porous 3D crystalline MOF with designed protein lattice, where two adjacent ferritin molecules along the C4 symmetry axes are bridged by four dinuclear or tetranuclear nickel clusters depending on Ni2+ concentration. This work provides a simple approach for precise control over a binary protein–metal crystalline framework, and the resulting MOFs exhibited inherent ferroxidase activity and peroxidase‐like catalytic activity. [ABSTRACT FROM AUTHOR]