Mimicking Molecular Chaperones to Regulate Protein Folding

Wireframe DNA Origami Capable of Vertex-protruding Transformation

Regulating dynamic behavior of the designed molecular structures provides a foundation for the construction of functional molecular devices. DNA nanotechnology allows conformational changes in two-dimensional and three-dimensional DNA origami nanostructures by introducing flexibility between the faces of the structures. However, dynamic transformations in wireframe DNA origami, composed solely of vertices and edges, remain challenging due to vertex-specific flexibility. We report a wireframe DNA origami capable of vertex-protruding transformation between the open- and closed-form with eight protruding vertices. This reversible transformation is driven by DNA hybridization and a toehold-mediated strand displacement reaction. Spacer strands between vertices and edges were designed to introduce flexibility. Coarse-grained molecular dynamics simulations demonstrated that a longer spacer increases conformational flexibility and can achieve the narrow angles required for the vertex-protruding transformation. The experimental results showed the successful assembly of the open-form structure under optimized salt conditions, as visualized through transmission electron microscopy images. Furthermore, the transformation between the open- and closed-form structures was demonstrated by the sequential addition of signal strands. This vertex-protruding transformation mechanism will expand the design approach of dynamic DNA nanostructures and help develop functional molecular devices for artificial molecular systems.

Biopolymer based Fibrous Aggregate Materials for Diagnosis and Treatment: Design, Manufacturing, and Applications

Biopolymer-based fibrous aggregate materials (BFAMs) have gained increasing attention in biomedicine due to their excellent biocompatibility, processability, biodegradability, and multifunctionality. Especially, the medical applications of BFAMs demand advanced structure, performance, and function, which conventional trial-and-error methods struggle to provide. This necessitates the rational selection of materials and manufacturing methods to design BFAMs with various intended functions and structures. This review summarizes the current progress in raw material selection, structural and functional design, processing technology, and application of BFAMs. Additionally, the challenges encountered during the development of BFAMs are discussed, along with perspectives for future research offered.

Autonomous Abiotic Thermal Protectant for Immunoglobulin G: Reducing the Need for Cold Chain Storage

Antibodies are vital biologic therapeutics, but their impact is limited by thermal instability. This requires maintaining a cold chain, from the point of manufacture to the point of use. We report an approach that could reduce the need for a cold chain. We present a thermal protectant (TP) for immunoglobulin G (IgG) that mimics the behavior of the heat shock protein HSP60. This hydrogel copolymer nanoparticle shows minimal affinity for IgG at or below 25 °C. As temperatures rise and approach the proteins melting temperature (Tm), the TP undergoes an autonomous phase transition (∼27 °C), above which the TP shows high affinity for IgG sequestering and stabilizing IgG at temperatures far above Tm. As temperatures return to RT, the TP reverts to its water-swollen state, allowing any metastable proteins time to refold to their native state before being released. The optimized TP has very low IgG molar capacity, effectively isolating and preventing aggregation at elevated temperatures.

Natural Spy Chaperone Mimic: Tailored Nanochaperone with Electrostatic-Hydrophobic Synergy To Enhance Protein Folding Regulation

Protein folding regulation is of great significance for maintaining protein structures and biological functions. This fundamental process is assisted by molecular chaperones, which act in inhibiting undesired protein aggregation and facilitating misfolded protein refolding. Inspired by the unique structure and ingenious mechanisms of natural Spy chaperones, we innovate a nanochaperone-guided protein folding strategy by rationally designed nanochaperones (nChaps) with customizable surface structures and properties. In this strategy, the nChaps with tunable charged surfaces can first rapidly capture different client proteins through long-range electrostatic attraction, similar to Spy. Subsequently, the captured proteins can be dynamically bound into the Spy-mimetic hydrophobic microdomains via short-range hydrophobic interactions. As a result, the client proteins are sequestered and stabilized in the chaperone-mimicking confined spaces on the surface of nChaps, thereby facilitating dynamic regulation of protein folding through an electrostatic-hydrophobic synergy mechanism. Moreover, benefiting from the adjustable charge and multiple hydrophobic microdomains, this biomimetic nChap potentiates protein stability at harsh temperatures and long-term storage, which is hardly achieved by natural Spy. Additionally, this strategy is applicable to 9 different proteins with varying isoelectric points and molecular weights, showing superior generality than Spy. Therefore, this work provides new perspectives in developing an advanced strategy for enhanced protein folding regulation.

Nano-Chaperones: Bridging Therapeutics for Amyloid Aggregation in Alzheimer's Disease and Type-2 Diabetes Mellitus

Nano-chaperones represent an innovative therapeutic approach targeting amyloid aggregation in Alzheimer's disease (AD) and Type-2 diabetes mellitus (T2DM), two diseases linked by similar pathogenic mechanisms involving protein misfolding and insulin resistance. Current treatments primarily address symptoms, yet nano-chaperones can potentially intervene at the molecular level by mimicking natural chaperone proteins to prevent or reverse amyloid aggregation. In AD, nano-chaperones target amyloid-beta (Aβ) peptides, reducing neurotoxicity and preserving neuronal function, while in T2DM, they inhibit islet amyloid polypeptide (IAPP) aggregation, alleviating cytotoxic stress on pancreatic β-cells. These nanoparticles exhibit a dual capacity for cellular penetration and selectivity in interacting with misfolded proteins, showing promise in mitigating the shared amyloidogenic pathways of both diseases. Preclinical studies have demonstrated significant reductions in amyloid toxicity with potential applications in crossing the blood-brain barrier (BBB) to enhance central nervous system (CNS) delivery. Nano-chaperones transformative role in developing multi-targeted precision therapies for complex diseases is highlighted, underscoring their capacity to modulate disease progression through targeted biomimetic interactions. Nano-chaperone designs for clinical application focus on enhancing therapeutic efficacy and safety. This innovative approach may redefine treatment paradigms for amyloid-related diseases, offering a new frontier in personalized medicine.

Advances in the chemical synthesis of human proteoforms

Access to structurally-defined human proteoforms is essential to the biochemical studies on human health and medicine. Chemical protein synthesis provides a bottom-up and atomic-resolution approach for the preparation of homogeneous proteoforms bearing any number of post-translational modifications of any structure, at any position, and in any combination. In this review, we summarize the development of chemical protein synthesis, focusing on the recent advances in synthetic methods, product characterizations, and biomedical applications. By analyzing the chemical protein synthesis studies on human proteoforms reported to date, this review demonstrates the significant methodological improvements that have taken place in the field of human proteoform synthesis, especially in the last decade. Our analysis shows that although further method development is needed, all the human proteoforms could be within reach in a cost-effective manner through a divide-and-conquer chemical protein synthesis strategy. The synthetic proteoforms have been increasingly used to support biomedical research, including spatial-temporal studies and interaction network analysis, activity quantification and mechanism elucidation, and the development and evaluation of diagnostics and therapeutics.

Optimal st-PMMA/C60 helical inclusion complexes via tunable energy landscapes for the application of an Ag SERS-active substrate

In bio-inspired systems, the hierarchical structures of biomolecules are mimicked to impart desired functions to self-assembled materials. However, these hierarchical architectures are based on multicomponent systems, which require not only a well defined primary structure of functional molecules but also the programming of self-assembly pathways. In this study, we investigate pathway complexity in the energy landscape of the syndiotactic poly(methyl methacrylate) (st-PMMA)/C60/toluene complex system, where C60 and toluene serve as guests in the st-PMMA helical host. Structural characterization revealed that st-PMMA preferentially wraps around C60, forming a thermodynamically favorable helical inclusion complex (HIC). However, during the preparation of the st-PMMA/C60 HIC, a lengthy guest-exchange pathway was discovered, where the st-PMMA/toluene HIC transformed into the st-PMMA/C60 HIC. This pathway complexity may hinder the formation of the st-PMMA/C60 HIC within a feasible timeframe. Given that the energy landscape can be modulated by temperature, the st-PMMA host can directly wrap around C60 in higher temperature ranges, thereby bypassing the guest-exchange process and increasing the st-PMMA/C60 HIC formation efficiency. Additionally, after self-assembly programming, the st-PMMA/C60 HIC can serve as an excellent photochemical reduction site. The well dispersed nanodomains of the st-PMMA/C60 HICs act as nanoparticle templates for surface-enhanced Raman scattering (SERS) hotspot fabrication. We successfully utilized these HIC templates to synthesize self-assembled SERS-active silver nanoparticle arrays, demonstrating their potential for use in chemical sensing applications. In summary, a clear energy landscape can guide supramolecular engineering to achieve the desired supramolecular architectures by selecting appropriate self-assembly pathways.

Thermo-sensitive polycaprolactone coacervates for preventing protein aggregation under thermal stress

Inspired from heat shock proteins (HSPs), a thermo-sensitive coacervate-forming polycaprolactone (CPCL) was designed as a natural chaperone mimic to protect proteins from thermal stress. Unlike the coil-globule polymers of poly(N-isopropyl acrylamide) (PNIPAM), the as-designed CPCL underwent a partial dehydration during heating, characterizing it as a coacervate-forming polymer. With its ability to transform between the coil and coacervate states in response to temperature, theCPCL spontaneously captured and released targeted proteins, thereby behaving like a natural chaperone of HSPs. Remarkably, compared with the PNIPAM homopolymer, the CPCL provided more efficient protection for proteins by inhibiting heat-induced aggregation above the melting temperature (Tm). Taken together, we envision that the CPCL with excellent biodegradability and biocompatibility could be a safe excipient for protein protection against thermal damage without separation.

ER Oxidoreductin 1-Like Activity of Cyclic Diselenides Drives Protein Disulfide Isomerase in an Electron Relay System

Disulfide formation generally involves a two-electron oxidation reaction between cysteine residues. Additionally, disulfide formation is an essential post-translational modification for the structural maturation of proteins. This oxidative folding is precisely controlled by an electron relay network constructed by protein disulfide isomerase (PDI), with a CGHC sequence as the redox-active site, and its family enzymes. Creating reagents that mimic the functions of these enzymes facilitates folding during chemical protein synthesis. In this study, we aimed to imitate a biological electron relay system using cyclic diselenide compounds as surrogates for endoplasmic reticulum oxidoreductin 1 (Ero1), which is responsible for the re-oxidation of PDI. Oxidized PDI (PDIox) introduces disulfide bonds into substrate proteins, resulting in its conversion to reduced PDI (PDIred). The PDIred is then re-oxidized to PDIox by a coexisting cyclic diselenide compound, thereby restoring the function of PDI as a disulfide-forming agent. The produced diselenol state is readily oxidized to the original diselenide state with molecular oxygen, continuously sustaining the PDI catalytic cycle. This artificial electron relay system regulating enzymatic PDI function effectively promotes the oxidative folding of disulfide-containing proteins, such as insulin - a hypoglycemic formulation - by enhancing both yield and reaction velocity.

Biomimetic Folding Strategies for Chemical Synthesis of Disulfide-Bonded Peptides and Proteins

Disulfide-bonded peptides and proteins, including hormones, toxins, growth factors, and others, are abundant in living organisms. These molecules play crucial physiological roles such as regulating cell and organism growth, development, and metabolism. They have also found widespread applications as drugs or tool molecules in biomedical and pharmaceutical research. However, the chemical synthesis of disulfide-bonded proteins is complicated by the challenges associated with their folding. This review focuses on the latest advancements in disulfide-bonded peptide and protein folding technologies. Particularly, it highlights biomimetic folding strategies that emulate the naturally occurring oxidative folding processes in nature. These strategies include chaperone-assisted folding, glycosylation-assisted folding, and organic-based oxidative folding methods. The review also anticipates future directions in folding technology. Such research offers innovative approaches for the chemical synthesis of complex proteins that are otherwise difficult to fold.

Functional nanochaperones for PEGylated insulin delivery in long-term glycemic control

PEGylation is a promising strategy for modulating the physicochemical properties and improving the therapeutic efficacy of protein drugs. However, the application of multi-PEGylation frequently results in diminished protein activity. A single low molecular weight PEG (5 kDa) modified at the amino terminus of the B chain preserves the biological activity of insulin and moderately improves its pharmacokinetics. Nonetheless, this modification offers limited protein stabilization. Furthermore, overdoses still carry the risk of hypoglycemia, posing challenges for the clinical application of PEGylated insulin. Here, we constructed multifunctional nanochaperones featuring phenylboronic acid (PBA) modified hydrophobic microdomains and nitrilotriacetic acid (NTA)-based coordination domains (PN-nChaps) for PEGylated insulin delivery. This delivery strategy effectively overcomes the limitations associated with PEGylation by enhancing the stability and reducing the immunogenicity of PEGylated insulin, while enabling glucose-responsive controlled release. PEGylated insulin with nanochaperone carrier demonstrates a prolonged half-life (t1/2 = 18.66 h), facilitates on-demand release, and minimizes the risk of hypoglycemia. This approach provides a safe and effective strategy for long-term glycemic management in diabetic patients.

Engineering Core/Ligands Interfacial Anchors of Nanoparticles for Efficiently Inhibiting Both Aβ and Amylin Fibrillization

Accurate construction of artificial nano-chaperones' structure is crucial for precise regulation of protein conformational transformation, facilitating effective treatment of proteopathy. However, how the ligand-anchors of nano-chaperones affect the spatial conformational changes in proteins remains unclear, limiting the development of efficient nano-chaperones. In this study, three types of gold nanoparticles (AuNPs) with different core/ligands interface anchor structures (Au─NH─R, Au─S─R, and Au─C≡C─R, R = benzoic acid) are synthesized as an ideal model to investigate the effect of interfacial anchors on Aβ and amylin fibrillization. Computational results revealed that the distinct interfacial anchors imparted diverse distributions of electrostatic potential on the nanointerface and core/ligands bond strength of AuNPs, leading to differential interactions with amyloid peptides. Experimental results demonstrated that all three types of AuNPs exhibit site-specific inhibitory effects on Aβ40 fibrillization due to preferential binding. For amylin, amino-anchored AuNPs demonstrate strong adsorption to multiple sites on amylin and effectively inhibit fibrillization. Conversely, thiol- and alkyne-anchored AuNPs adsorb at the head region of amylin, promoting folding and fibrillization. This study not only provided molecular insights into how core/ligands interfacial anchors of nanomaterials induce spatial conformational changes in amyloid peptides but also offered guidance for precisely engineering artificial-chaperones' nanointerfaces to regulate the conformational transformation of proteins.

Engineered polymer nanoparticles as artificial chaperones facilitating the selective refolding of denatured enzymes

Molecular chaperones assist in protein refolding by selectively binding to proteins in their nonnative states. Despite progress in creating artificial chaperones, these designs often have a limited range of substrates they can work with. In this paper, we present molecularly imprinted flexible polymer nanoparticles (nanoMIPs) designed as customizable biomimetic chaperones. We used model proteins such as cytochrome c, laccase, and lipase to screen polymeric monomers and identify the most effective formulations, offering tunable charge and hydrophobic properties. Utilizing a dispersed phase imprinting approach, we employed magnetic beads modified with destabilized whole-protein as solid-phase templates. This process involves medium exchange facilitated by magnetic pulldowns, resulting in the synthesis of nanoMIPs featuring imprinted sites that effectively mimic chaperone cavities. These nanoMIPs were able to selectively refold denatured enzymes, achieving up to 86.7% recovery of their activity, significantly outperforming control samples. Mechanistic studies confirmed that nanoMIPs preferentially bind denatured rather than native enzymes, mimicking natural chaperone interactions. Multifaceted analyses support the functionality of nanoMIPs, which emulate the protective roles of chaperones by selectively engaging with denatured proteins to inhibit aggregation and facilitate refolding. This approach shows promise for widespread use in protein recovery within biocatalysis and biomedicine.

Controlled Refolding of Denatured IL-12 Using In Situ Antigen-Capturing Nanochaperone Remarkably Reduces the Systemic Toxicity and Enhances Cancer Immunotherapy

Cytokines are powerful in cancer immunotherapy, however, their therapeutic potential is limited by the severe systemic toxicity. Here a potent strategy to reduce the toxicity of systemic cytokine therapy by delivering its denatured form using a finely designed nanochaperone, is described. It is demonstrated that even if the denatured protein cargos are occasionally released under normal physiological conditions they are still misfolded, while can effectively refold into native states and release to function in tumor microenvironment. Consequently, the systemic toxicity of cytokines is nearly completely overcome. Moreover, an immunogenic cell death (ICD)-inducing chemotherapeutic is further loaded and delivered to tumor using this nanochaperone to trigger the release of tumor-associated antigens (TAAs) that are subsequently captured in situ by nanochaperone and then reflows into lymph nodes (LNs) to promote antigen cross-presentation. This optimized personalized nanochaperone-vaccine demonstrates unprecedented suppressive effects against large, advanced tumors, and in combination with immune checkpoint blockade (ICB) therapy results in a significant abscopal effect and inhibition of postoperative tumor recurrence and metastasis. Hence, this approach provides a simple and universal delivery strategy to reduce the systemic toxicities of cytokines, as well as provides a robust personalized cancer vaccination platform, which may find wide applications in cancer immunotherapy.

The role of molecular chaperone CCT/TRiC in translation elongation: A literature review

Protein synthesis from mRNA is an energy-intensive and strictly controlled biological process. Translation elongation is a well-coordinated and multifactorial step in translation that ensures the accurate and efficient addition of amino acids to a growing nascent-peptide chain encoded in the sequence of messenger RNA (mRNA). Which undergoes dynamic regulation due to cellular state and environmental determinants. An expanding body of research points to translational elongation as a crucial process that controls the translation of an mRNA through multiple feedback mechanisms. Molecular chaperones are key players in protein homeostasis to keep the balance between protein synthesis, folding, assembly, and degradation. Chaperonin-containing tailless complex polypeptide 1 (CCT) or tailless complex polypeptide 1 ring complex (TRiC) is an essential eukaryotic molecular chaperone that plays an essential role in assisting cellular protein folding and suppressing protein aggregation. In this review, we give an overview of the factors that influence translation elongation, focusing on different functions of molecular chaperones in translation elongation, including how they affect translation rates and post-translational modifications. We also provide an understanding of the mechanisms by which the molecular chaperone CCT plays multiple roles in the elongation phase of eukaryotic protein synthesis.

Exploiting cyclodextrins as artificial chaperones to enhance enzyme protection through supramolecular engineering

We report a method of enzyme stabilisation exploiting the artificial protein chaperone properties of β-cyclodextrin (β-CD) covalently embedded in an ultrathin organosilica layer. Putative interaction points of this artificial chaperone system with the surface of the selected enzyme were studied in silico using a protein energy landscape exploration simulation algorithm. We show that this enzyme shielding method allows for drastic enhancement of enzyme stability under thermal and chemical stress conditions, along with broadening the optimal temperature range of the biocatalyst. The presence of the β-CD macrocycle within the protective layer supports protein refolding after treatment with a surfactant.

What can molecular assembly learn from catalysed assembly in living organisms?

Molecular assembly is the process of organizing individual molecules into larger structures and complex systems. The self-assembly approach is predominantly utilized in creating artificial molecular assemblies, and was believed to be the primary mode of molecular assembly in living organisms as well. However, it has been shown that the assembly of many biological complexes is "catalysed" by other molecules, rather than relying solely on self-assembly. In this review, we summarize these catalysed-assembly (catassembly) phenomena in living organisms and systematically analyse their mechanisms. We then expand on these phenomena and discuss related concepts, including catalysed-disassembly and catalysed-reassembly. Catassembly proves to be an efficient and highly selective strategy for synergistically controlling and manipulating various noncovalent interactions, especially in hierarchical molecular assemblies. Overreliance on self-assembly may, to some extent, hinder the advancement of artificial molecular assembly with powerful features. Furthermore, inspired by the biological catassembly phenomena, we propose guidelines for designing artificial catassembly systems and developing characterization and theoretical methods, and review pioneering works along this new direction. Overall, this approach may broaden and deepen our understanding of molecular assembly, enabling the construction and control of intelligent assembly systems with advanced functionality.

Tuning Phase Transition of Molecular Self-Assembly by Artificial Chaperones through Aromatic-Aromatic Interactions

The molecular chaperones are essential and play significant roles in controlling the protein phase transition and maintaining physiological homeostasis. However, manipulating phase transformation in biomimetic peptide self-assembly is still challenging. This work shows that an artificial chaperone modulates the energy landscape of supramolecular polymerization, thus controlling the phase transition of amyloid-like assemblies from crystals to hydrogels to solution. The absence of a chaperone allows the NapP to form crystals, while the presence of the chaperone biases the pathway to form nanofibrous hydrogels to soluble oligomers by adjusting the chaperone ratios. Mechanistic studies reveal that the aromatic-aromatic interaction is the key to trapping the molecules in a higher energy fold. Adding the chaperone relieves this restriction, lowers the energy barrier, and transforms the crystal into a hydrogel. This phase transformation can also be achieved in the macromolecular crowding environment, thus providing new insights into understanding molecular self-assembly in multiple component systems.

Chaperone Mimetic Strategy for Achieving Organic Room-Temperature Phosphorescence based on Confined Supramolecular Assembly

The development of organic materials that deliver room-temperature phosphorescence (RTP) is highly interesting for potential applications such as anticounterfeiting, optoelectronic devices, and bioimaging. Herein, a molecular chaperone strategy for controlling isolated chromophores to achieve high-performance RTP is demonstrated. Systematic experiments coupled with theoretical evidence reveal that the host plays a similar role as a molecular chaperone that anchors the chromophores for limited nonradiative decay and directs the proper conformation of guests for enhanced intersystem crossing through noncovalent interactions. For deduction of structure-property relationships, various structure-related descriptors that correlate with the RTP performance are identified, thus offering the possibility to quantitatively design and predict the phosphorescent behaviors of these systems. Furthermore, application in thermal printing is well realized for these RTP materials. The present work discloses an effective strategy for efficient construction of organic RTP materials, delivering a modular model which is expected to help expand the diversity of desirable RTP systems.

Development of self-cooperative nanochaperones with enhanced activity to facilitate protein refolding

Regulating protein folding including assisting de novo folding, preventing misfolding and aggregation, and facilitating refolding of proteins are of significant importance for retaining protein's biological activities. Here, we report a mixed shell polymeric micelle (MSPM)-based self-cooperative nanochaperone (self-CO-nChap) with enhanced activity to facilitate protein refolding. This self-CO-nChap was fabricated by introducing Hsp40-mimetic artificial carriers into the traditional nanochaperone to cooperate with the Hsp70-mimetic confined hydrophobic microdomains. The artificial carrier facilitates transfer and immobilization of client proteins into confined hydrophobic microdomains, by which significantly improving self-CO-nChap's capability to inhibit unfolding and aggregation of client proteins, and finally facilitating refolding. Compared to traditional nanochaperones, the self-CO-nChap significantly enhances the thermal stability of horseradish peroxidase (HRP) epicyclically under harsher conditions. Moreover, the self-CO-nChap efficiently protects misfolding-prone proteins, such as immunoglobulin G (IgG) antibody from thermal denaturation, which is hardly achieved using traditional nanochaperones. In addition, a kinetic partitioning mechanism was devised to explain how self-CO-nChap facilitates refolding by regulating the cooperative effect of kinetics between the nanochaperone and client proteins. This work provides a novel strategy for the design of protein folding regulatory materials, including nanochaperones.

Self-Assembly Nanochaperone with Tunable Hydrophilic-Hydrophobic Surface for Controlled Protein Refolding

Nanochaperones (nChaps) have significant potential to inhibit protein aggregation and assist in protein refolding. The interaction between nChaps and proteins plays an important role in nChaps performing chaperone-like functions, but the interaction mechanism remains elusive. In this work, a series of nChaps with tunable hydrophilic-hydrophobic surfaces are prepared, and the process of nChaps-assisted denatured protein refolding is systematically explored. It is found that an appropriate hydrophilic-hydrophobic balance on the nChap surface is critical for enhancing protein renaturation. This is because only the optimal interaction between nChap and protein can simultaneously guarantee the suitable capture and sufficient release of client proteins. The findings in this work will provide an effective reference for the design of nChaps and contribute to the development of the potential of nChaps in the future.

Amphiphilic dendrons as supramolecular holdase chaperones

The aggregation of incompletely or incorrectly folded proteins is implicated in diseases including Alzheimer's, cataracts, and other maladies. Natural systems express protein chaperones to prevent or even reverse harmful protein aggregation. Synthetic chaperone-like systems have sought to mimic the action of their biological counterparts but typically require substantial optimization and high concentrations to be functional, or lack programmability that would enable the targeting of specific protein substrates. Here we report a series of amphiphilic dendrons that undergo assembly and inhibit the aggregation of fragment 16-22 amyloid β protein (Aβ16-22). We show that monodisperse dendrons with hydrophilic tetraethylene glycol chains and a hydrophobic core based on naphthyl and benzyl ethers undergo supramolecular assembly in aqueous solutions to form sphere-like particles. The solubility of these dendrons and their assemblies is tuned by varying the relative sizes of their hydrophilic and hydrophobic regions. Two water-soluble dendrons are discovered and shown, via fluorescence experiments with rhodamine 6G, to generate a hydrophobic environment. Furthermore, we demonstrate that sub-stoichiometric concentrations of these amphiphilic dendrons stabilize Aβ16-22 peptide with respect to aggregation, mimicking the activity of holdase chaperones. Our results highlight the potential of these amphiphilic molecules as the basis for a novel approach to artificial chaperones that may address many of the challenges associated with existing synthetic chaperone mimics.

Holdase/Foldase Mimetic Nanochaperone Improves Antibody-Based Cancer Immunotherapy

Despite unprecedented successes of antibody-based cancer immunotherapy, the serious side effects and rapid clearance following systemic administration remain big challenges to realize its full potential. At the same time, combination immunotherapy using multiple antibodies has shown particularly promising in cancer treatment. It is noticed that the working mechanisms of natural holdase and foldase chaperone are desirable to overcome the limitations of therapeutic antibodies. Holdase chaperone stabilizes unfolded client and prevents it from activation and degradation, while foldase chaperone assists unfolded client to its native state to function. Here a holdase/foldase mimetic nanochaperone (H/F-nChap) to co-delivery two types of monoclonal antibodies (mAbs), αCD16 and αPDL1, and resiquimod (R848) is developed, which significantly improves cancer immunotherapy. The H/F-nChap presents holdase activity in blood and normal tissues that hides and protects mAbs from unnecessary targeted activation and degradation, thereby prolonging blood circulation and reducing immunotoxicity in vivo. Furthermore, H/F-nChap switches to foldase activity in the tumor microenvironment that exposes mAbs and releases R848 to enhance the engagement between NK cells and tumor cells and promote immune activation, respectively. The H/F-nChap represents a strategy for safe and spatiotemporal delivery of multiple mAbs, providing a promising platform for improved cancer immunotherapy.

Genome-wide analysis reveals Hsf1 maintains high transcript abundance of target genes controlled by strong constitutive promoter in Saccharomyces cerevisiae

BACKGROUND

In synthetic biology, the strength of promoter elements is the basis for precise regulation of target gene transcription levels, which in turn increases the yield of the target product. However, the results of many researches proved that excessive transcription levels of target genes actually reduced the yield of the target product. This phenomenon has been found in studies using different microorganisms as chassis cells, thus, it becomes a bottleneck problem to improve the yield of the target product.

RESULTS

In this study, promoters PGK1p and TDH3p with different strengths were used to regulate the transcription level of alcohol acetyl transferase encoding gene ATF1. The results demonstrated that the strong promoter TDH3p decreased the production of ethyl acetate. The results of Real-time PCR proved that the transcription level of ATF1 decreased rapidly under the control of TDH3p, and the unfolded protein reaction was activated, which may be the reason for the abnormal production caused by the strong promoter. RNA-sequencing analysis showed that the overexpression of differential gene HSP30 increased the transcriptional abundance of ATF1 gene and production of ethyl acetate. Interestingly, deletion of the heat shock protein family (e.g., Hsp26, Hsp78, Hsp82) decreased the production of ethyl acetate, suggesting that the Hsp family was also involved in the regulation of ATF1 gene transcription. Furthermore, the results proved that the Hsf1, an upstream transcription factor of Hsps, had a positive effect on alleviating the unfolded protein response and that overexpression of Hsf1 reprogramed the pattern of ATF1 gene transcript levels. The combined overexpression of Hsf1 and Hsps further increased the production of ethyl acetate. In addition, kinase Rim15 may be involved in this regulatory pathway. Finally, the regulation effect of Hsf1 on recombinant strains constructed by other promoters was verified, which confirmed the universality of the strategy.

CONCLUSIONS

Our results elucidated the mechanism by which Rim15-Hsf1-Hsps pathway reconstructed the repression of high transcription level stress and increased the production of target products, thereby providing new insights and application strategies for the construction of recombinant strains in synthetic biology.

Enhanced production of recombinant proteins in Corynebacterium glutamicum using a molecular chaperone

Protein synthesis in Corynebacterium glutamicum is critical for applications in biotechnology and medicine. However, the use of C. glutamicum for protein production is limited by its low expression and aggregation. To overcome these limitations, a molecular chaperone plasmid system was developed in this study to improve the efficiency of recombinant protein synthesis in C. glutamicum. The effect of molecular chaperones on target protein synthesis (Single-chain variable fragment, Scfv) under three different promoter strengths was tested. In addition, the plasmid containing the molecular chaperone and target protein was verified for growth stability and plasmid stability. This expression model was further validated using two recombinant proteins, human interferon-beta (Hifn) and hirudin variant III (Rhv3). Finally, the Rhv3 protein was purified, and analysis of Rhv3 activity confirmed that the use of a molecular chaperone led to an improvement in test protein synthesis. Thus, the use of molecular chaperones is believed to will improve recombinant proteins synthesis in C. glutamicum.

Polymeric nanoparticle-based nanovaccines for cancer immunotherapy

Therapeutic cancer vaccines, which are designed to amplify tumor-specific T cell responses, have been envisioned as one of the most powerful tools for effective cancer immunotherapy. However, increasing the potency, quality and durability of the vaccine response remains a big challenge. In recent years, materials-based delivery systems focusing on the co-delivery of antigens and adjuvants to enhance cancer vaccination therapy have attracted increasing interest. Among various materials, polymeric nanoparticles (NPs) with different physicochemical properties which can incorporate multiple immunological cues are of great interest. In this review, the recent progress in the design and construction of both ex vivo subunit and in situ cancer vaccines using polymeric NPs is summarized. Especially, we will focus on how these NPs improve the adjuvanticity of vaccines. The design principles of polymeric NPs for ex vivo subunit cancer vaccines and in situ cancer vaccination are also discussed. Finally, we want to briefly discuss molecular chaperones in cancer immunity and the applications of our unique self-assembly mixed shell polymeric micelle-based nanochaperones for cancer vaccines.

Gold Nanoclusters Enhance the Efficacy of the Polymer-Based Chaperone in Restoring and Maintaining the Native Conformation of Human Islet Amyloid Polypeptide

The misfolding and un-natural fibrillation of proteins/peptides are associated with many conformation diseases, such as human islet amyloid polypeptide (hIAPP) in type 2 diabetes (T2D). Inspired by molecular chaperones maintaining protein homeostasis in vivo, many polymer-based artificial chaperones were introduced to regulate protein/peptide folding and fibrillation. However, the pure polymer chaperones prefer to agglomerate into large-size micelles in the physiological environment and thus lose their chaperone functions, which greatly restricts the application of polymer-based chaperones. Here, we designed and prepared a core-shell artificial chaperone based on a dozen poly-(N-isopropylacrylamide-co-N-acryloyl-O-methylated-l-arginine) (PNAMR) anchored on a gold-nanocluster (AuNC) core. The introduction of the AuNC core significantly reduced the size and enhanced the efficacy and stability of polymer-based artificial chaperones. The PNAMR@AuNCs, with a diameter of 2.5 ± 0.5 nm, demonstrated exceptional ability in maintaining the natively unfolded conformation of protein away from the misfolding and the following fibrillation by directly binding to the natively unfolded monomolecular hIAPP and hence in preventing their conversion into toxic oligomers. More excitingly, the PNAMR@AuNCs were able to restore the natural unfolded conformation of hIAPP via dissolving the β-sheet-rich hIAPP fibrils. Considering the uniform molecular mechanism of protein misfolding and fibrillation in conformation disorders, this finding provides a generic therapeutic strategy for neurodegenerative diseases and other conformation diseases by using PNAMR@AuNC artificial chaperones to restore and maintain the native conformation of amyloid proteins.

Laboratory Scale Production of Complex Proteins Using Charge Complimentary Nanoenvironments

Protein refolding is a crucial procedure in bacterial recombinant expression. Aggregation and misfolding are the two challenges that can affect the overall yield and specific activity of the folded proteins. We demonstrated the in vitro use of nanoscale "thermostable exoshells" (tES) to encapsulate, fold and release diverse protein substrates. With tES, the soluble yield, functional yield, and specific activity increased from 2-fold to >100-fold when compared to folding in its absence. On average, the soluble yield was determined to be 6.5 mg/100 mg of tES for a set of 12 diverse substrates evaluated. The electrostatic charge complementation between the tES interior and the protein substrate was considered as the primary determinant for functional folding. We thus describe a useful and simple method for in vitro folding that has been evaluated and implemented in our laboratory.

Thermo-Gelling Dendronized Chitosans for Modulating Protein Activity

Regulation of protein activity is important in their applications for biomedicine and therapeutics. Here, an approach for the regulation of protein bioactivity through molecular confinement provided by oligoethylene glycol (OEG)-based dendronized chitosan (DCS) hydrogels is reported. Structural effects on their thermoresponsiveness are investigated. The highly transparent hydrogels are formed from thermoresponsive DCSs through their thermal dehydration and exhibit an intriguing reversible sol-gel transition property when triggered at physiological temperatures. The thermo-gelling behavior and mechanical strength of these hydrogels are investigated, and possible effects from hydrophobicity of the OEG dendrons, grafting rates of the dendrons on the chitosan main chain, and solid content of polymers are examined. These DCS hydrogels are found to have lamellar morphologies and can provide characteristic hydrophobicity microenvironments formed through the crowded OEG dendrons, which show a higher level of confinement to guest proteins. This allows the DCS hydrogels remarkable activity protection capability to proteins. Furthermore, these DCS hydrogels inherit the degradability from chitosan, allowing protein release from these hydrogels through the controllable ways without impairing their activities.

The regulatory role of endoplasmic reticulum chaperone proteins in neurodevelopment

The endoplasmic reticulum (ER) is the largest tubular reticular organelle spanning the cell. As the main site of protein synthesis, Ca2+ homeostasis maintenance and lipid metabolism, the ER plays a variety of essential roles in eukaryotic cells, with ER molecular chaperones participate in all these processes. In recent years, it has been reported that the abnormal expression of ER chaperones often leads to a variety of neurodevelopmental disorders (NDDs), including abnormal neuronal migration, neuronal morphogenesis, and synaptic function. Neuronal development is a complex and precisely regulated process. Currently, the mechanism by which neural development is regulated at the ER level remains under investigation. Therefore, in this work, we reviewed the recent advances in the roles of ER chaperones in neural development and developmental disorders caused by the deficiency of these molecular chaperones.

Fabry disease: Mechanism and therapeutics strategies

Fabry disease is a monogenic disease characterized by a deficiency or loss of the α-galactosidase A (GLA). The resulting impairment in lysosomal GLA enzymatic activity leads to the pathogenic accumulation of enzymatic substrate and, consequently, the progressive appearance of clinical symptoms in target organs, including the heart, kidney, and brain. However, the mechanisms involved in Fabry disease-mediated organ damage are largely ambiguous and poorly understood, which hinders the development of therapeutic strategies for the treatment of this disorder. Although currently available clinical approaches have shown some efficiency in the treatment of Fabry disease, they all exhibit limitations that need to be overcome. In this review, we first introduce current mechanistic knowledge of Fabry disease and discuss potential therapeutic strategies for its treatment. We then systemically summarize and discuss advances in research on therapeutic approaches, including enzyme replacement therapy (ERT), gene therapy, and chaperone therapy, as well as strategies targeting subcellular compartments, such as lysosomes, the endoplasmic reticulum, and the nucleus. Finally, the future development of potential therapeutic strategies is discussed based on the results of mechanistic studies and the limitations associated with these therapeutic approaches.

GP, Gopalakrishnan AV. Role of Immune Cells and Receptors in Cancer Treatment: An Immunotherapeutic Approach

Cancer immunotherapy moderates the immune system's ability to fight cancer. Due to its extreme complexity, scientists are working to put together all the puzzle pieces to get a clearer picture of the immune system. Shreds of available evidence show the connection between cancer and the immune system. Immune responses to tumors and lymphoid malignancies are influenced by B cells, γδT cells, NK cells, and dendritic cells (DCs). Cancer immunotherapy, which encompasses adoptive cancer therapy, monoclonal antibodies (mAbs), immune checkpoint therapy, and CART cells, has revolutionized contemporary cancer treatment. This article reviews recent developments in immune cell regulation and cancer immunotherapy. Various options are available to treat many diseases, particularly cancer, due to the progress in various immunotherapies, such as monoclonal antibodies, recombinant proteins, vaccinations (both preventative and curative), cellular immunotherapies, and cytokines.

In Situ Antigen-Capturing Nanochaperone Toward Personalized Nanovaccine for Cancer Immunotherapy

Personalized cancer vaccination using nanomaterials holds great potential for cancer immunotherapy. Here, a nanochaperone (PBA-nChap) is tailored for in situ capture of tumor-associated antigens (TAAs) to improve cancer immunotherapy. The PBA-nChap is capable of i) efficiently capturing TAAs in situ; ii) protecting TAAs from degradation; iii) transporting TAAs to antigen-presenting cells and promoting cross-presentation. Intratumor injection of PBA-nChap in combination with pretreatment with photodynamic therapy (PDT) significantly enhances immune response and exhibits excellent antitumor efficacy. Moreover, nanovaccine prepared by simply co-culturing PBA-nChap with tumor cell fragments from surgery resected primary tumor in vitro synergized with immune checkpoint blockade (ICB) therapy can effectively inhibit tumor recurrence and metastasis after an operation. This work provides a promising platform for personalized cancer vaccination.

Interaction of Human Resistin with Human Islet Amyloid Polypeptide at Charged Phospholipid Membranes

An X-ray reflectivity study on the interaction of recombinant human resistin (hRes) with fibrillation-prone human islet amyloid polypeptide (hIAPP) at anionic phospholipid Langmuir films as model membranes is presented. Aggregation and amyloid formation of hIAPP is considered the main mechanism of pancreatic β-cell loss in patients with type 2 diabetes mellitus. Resistin shows a chaperone-like ability, but also tends to form aggregates by itself. Resistin and hIAPP cross multiply metabolism pathways. In this study, we researched the potential protective effects of resistin against hIAPP-induced lipid membrane rupture. The results demonstrate that resistin can inhibit or prevent hIAPP adsorption even in the presence of aggregation-promoting negatively charged lipid interfaces. Moreover, we found strong hydrophobic interactions of resistin at the bare buffer-air interface.

Functional Genomics Identified Novel Genes Involved in Growth at Low Temperatures in Listeria monocytogenes

Listeria monocytogenes (Lm) is a foodborne pathogen that can cause severe human illness. Standard control measures for restricting bacterial growth, such as refrigeration, are often inadequate as Lm grows well at low temperatures. To identify genes involved in growth at low temperatures, a powerful functional genomics method Tn-seq was performed in this study. This genome-wide screening comprehensively identified the known and novel genetic determinants involved in low-temperature growth. A novel gene lmo1366, encoding rRNA methyltransferase, was identified to play an essential role in Lm growth at 16°C. In contrast, the inactivation of lmo2301, a gene encoding the terminase of phage A118, significantly enhanced the growth of Lm at 16°C. The deletion of lmo1366 or lmo2301 resulted in cell morphology alterations and impaired the growth rate in milk and other conditions at low temperatures. Transcriptomic analysis revealed that the Δlmo1366 and Δlmo2301 mutants exhibited altered transcriptional patterns compared to the wild-type strain at 16°C with significant differences in genes involved in ribosome structural stability and function, and membrane biogenesis, respectively. This work uncovered novel genetic determinants involved in Lm growth at 16°C, which could lead to a better understanding of how bacteria survive and multiply at low temperatures. Furthermore, these findings could potentially contribute to developing novel antibacterial strategies under low-temperature conditions.

IMPORTANCEListeria monocytogenes is a Gram-positive pathogen that contributes to foodborne outbreaks due to its ability to survive at low temperatures. However, the genetic determinants of Lm involved in growth at low temperatures have not been fully defined. Here, the genetic determinants involved in the low-temperature growth of Lm were comprehensively identified on a genome-wide scale by Tn-seq. The gene lmo1366, encoding rRNA methyltransferase, was identified essential for growth under low-temperature conditions. On the other hand, the gene lmo2301, encoding terminase of phage A118, plays a negative role in bacterial growth at low temperatures. The transcriptomic analysis revealed the potential mechanisms. These findings lead to a better understanding of how bacteria survive and multiply at low temperatures and could provide unique targets for novel antibacterial strategies under low-temperature conditions.

Engineering Nanointerfaces of Au25 Clusters for Chaperone-Mediated Peptide Amyloidosis

Synthetic nanomaterials possessing biomolecular-chaperone functions are good candidates for modulating physicochemical interactions in many bioapplications. Despite extensive research, no general principle to engineer nanomaterial surfaces is available to precisely manipulate biomolecular conformations and behaviors, greatly limiting attempts to develop high-performance nanochaperone materials. Here, we demonstrate that, by quantifying the length (-SC_xR^±, x = 3-11) and charges (R^- = -COO^-, R⁺ = -NH₃⁺) of ligands on Au₂₅ gold nanochaperones (AuNCs), simulating binding sites and affinities of amyloid-like peptides with AuNCs, and probing peptide folding and fibrillation in the presence of AuNCs, it is possible to precisely manipulate the peptides' conformations and, thus, their amyloidosis via customizing AuNCs nanointerfaces. We show that intermediate-length liganded AuNCs with a specific charge chaperone peptides' native conformations and thus inhibit their fibrillation, while other types of AuNCs destabilize peptides and promote their fibrillation. We offer a microscopic molecular insight into peptide identity on AuNCs and provide a guideline in customizing nanochaperones via manipulating their nanointerfaces.

Engineered Nanoparticle-Protein Interactions Influence Protein Structural Integrity and Biological Significance

Engineered nanoparticles (ENPs) are artificially synthesized particles with unique physicochemical properties. ENPs are being extensively used in several consumer items, elevating the probability of ENP exposure to biological systems. ENPs interact with various biomolecules like lipids, proteins, nucleic acids, where proteins are most susceptible. The ENP-protein interactions are mostly studied for corona formation and its effect on the bio-reactivity of ENPs, however, an in-depth understanding of subsequent interactive effects on proteins, such as alterations in their structure, conformation, free energy, and folding is still required. The present review focuses on ENP-protein interactions and the subsequent effects on protein structure and function followed by the therapeutic potential of ENPs for protein misfolding diseases.

Size-Dependent Cytotoxic and Molecular Study of the Use of Gold Nanoparticles against Liver Cancer Cells

The size of nanomaterials influences physicochemical parameters, and variations in the size of nanomaterials can have a significant effect on their biological activities in cells. Due to the potential applicability of nanoparticles (NPs), the current work was designed to carry out a size-dependent study of gold nanoparticles (GNPs) in different dimensions, synthesized via a colloidal solution process. Three dissimilar-sized GNPs, GNPs-1 (10–15 nm), GNPs-2 (20–30 nm), and GNPs-3 (45 nm), were prepared and characterized via transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), hydrodynamic size, zeta potential, and UV-visible spectroscopy, and applied against liver cancer (HepG2) cells. Various concentrations of GNPs (1, 2, 5, 10, 50, and 100 µg/mL) were applied against the HepG2 cancer cells to assess the percentage of cell viability via MTT and NRU assays; reactive oxygen species (ROS) generation was also used. ROS generation was increased by 194%, 164%, and 153% for GNPs-1, GNPs-2, and GNPs-3, respectively, in the HepG2 cells. The quantitative polymerase chain reaction (qPCR) data for the HepG2 cells showed up-regulation in gene expression of apoptotic genes (Bax, p53, and caspase-3) when exposed to the different-sized GNPs, and defined their respective roles. Based on the results, it was concluded that GNPs of different sizes have the potential to induce cancer cell death.

One-pot synthesis of high-concentration mixed-shell polymeric micelles as nanochaperones for the renaturation of bulk proteins

A one-pot synthesis of high-concentration mixed-shell polymeric micelles and synthetic nanoparticles can be used to assist the refolding of bulk denatured proteins and stabilize native proteins for long-term storage.

Rational Design of Protein-Specific Folding Modifiers

Protein-folding can go wrong in vivo and in vitro, with significant consequences for the living organism and the pharmaceutical industry, respectively. Here we propose a design principle for small-peptide-based protein-specific folding modifiers. The principle is based on constructing a "xenonucleus", which is a prefolded peptide that mimics the folding nucleus of a protein. Using stopped-flow kinetics, NMR spectroscopy, Förster resonance energy transfer, single-molecule force measurements, and molecular dynamics simulations, we demonstrate that a xenonucleus can make the refolding of ubiquitin faster by 33 ± 5%, while variants of the same peptide have little or no effect. Our approach provides a novel method for constructing specific, genetically encodable folding catalysts for suitable proteins that have a well-defined contiguous folding nucleus.

Pickering-Droplet-Derived MOF Microreactors for Continuous-Flow Biocatalysis with Size Selectivity

Enzymatic microarchitectures with spatially controlled reactivity, engineered molecular sieving ability, favorable interior environment, and industrial productivity show great potential in synthetic protocellular systems and practical biotechnology, but their construction remains a significant challenge. Here, we proposed a Pickering emulsion interface-directed synthesis method to fabricate such a microreactor, in which a robust and defect-free MOF layer was grown around silica emulsifier stabilized droplet surfaces. The compartmentalized interior droplets can provide a biomimetic microenvironment to host free enzymes, while the outer MOF layer secludes active species from the surroundings and endows the microreactor with size-selective permeability. Impressively, the thus-designed enzymatic microreactor exhibited excellent size selectivity and long-term stability, as demonstrated by a 1000 h continuous-flow reaction, while affording completely equal enantioselectivities to the free enzyme counterpart. Moreover, the catalytic efficiency of such enzymatic microreactors was conveniently regulated through engineering of the type or thickness of the outer MOF layer or interior environments for the enzymes, highlighting their superior customized specialties. This study provides new opportunities in designing MOF-based artificial cellular microreactors for practical applications.

A general approach to protein folding using thermostable exoshells

In vitro protein folding is a complex process which often results in protein aggregation, low yields and low specific activity. Here we report the use of nanoscale exoshells (tES) to provide complementary nanoenvironments for the folding and release of 12 highly diverse protein substrates ranging from small protein toxins to human albumin, a dimeric protein (alkaline phosphatase), a trimeric ion channel (Omp2a) and the tetrameric tumor suppressor, p53. These proteins represent a unique diversity in size, volume, disulfide linkages, isoelectric point and multi versus monomeric nature of their functional units. Protein encapsulation within tES increased crude soluble yield (3-fold to >100-fold), functional yield (2-fold to >100-fold) and specific activity (3-fold to >100-fold) for all the proteins tested. The average soluble yield was 6.5 mg/100 mg of tES with charge complementation between the tES internal cavity and the protein substrate being the primary determinant of functional folding. Our results confirm the importance of nanoscale electrostatic effects and provide a solution for folding proteins in vitro.

A Balance Between Capture and Release: How Nanochaperones Regulate Refolding of Thermally Denatured Proteins

Nanochaperones have been designed and used for regulating the (re)folding of proteins, treating protein misfolding-related diseases, and, more recently, in drug delivery. Despite various successes, a complete understanding of the working mechanisms remains elusive, which represents a challenge for the realization of their full potential. Here, we thoroughly investigated the functioning of differently charged nanochaperones that regulate the refolding of thermally denatured lysozyme. We found that the balance between the capture and release of lysozyme clients that are controlled by nanochaperones plays a key role in regulating refolding. More importantly, the findings could be applied to other enzymes with various physicochemical properties. On the basis of these results, we could recover the activity of enzymes with high efficiency either after 20 days of storage at 40 °C or heating at high temperatures for 30-60 min. Our results provide important new design strategies for nanochaperone systems to improve their properties and expand their applications.

General method to stabilize mesophilic proteins in hyperthermal water

The stability of protein structures and biological functions at normal temperature is closely linked with the universal aqueous environment of organisms. Preserving bioactivities of proteins in hyperthermia water would expand their functional capabilities beyond those in native environments. However, only a limited number of proteins derived from hyperthermophiles are thermostable at elevated temperatures. Triggered by this, here we describe a general method to stabilize mesophilic proteins in hyperthermia water. The mesophilic proteins, protected by amphiphilic polymers with multiple binding sites, maintain their secondary and tertiary structures after incubation even in boiling water. This approach, outside the conventional environment for bioactivities of mesophilic proteins, provides a general strategy to dramatically increase the T_m (melting temperature) of mesophilic proteins without any changes to amino sequences of the native proteins. Current work offers a new insight with protein stability engineering for potential application, including vaccine storage and enzyme engineering.

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Preserving bioactivities of proteins in hyperthermia water is promising.

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Amphiphilic polymers could protect mesophilic proteins even in boiling water.

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Mesophilic proteins protected by amphiphilic polymers show dramatically increased T_m.

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The method offers application prospect for vaccine storage and enzyme engineering.

Stacking of nanorings to generate nanotubes for acceleration of protein refolding

Self-assembly and photoisomerization of azobenzene-based amphiphilic molecules produced nanorings with an inner diameter of 25 nm and lengths of <40 nm. The nanorings, which consisted of a single bilayer membrane of the amphiphiles, retained their morphology in the presence of a stacking inhibitor; whereas in the absence of the inhibitor, the nanorings stacked into short nanotubes (<500 nm). When subjected to mild heat treatment, these nanotubes joined end-to-end to form nanotubes with lengths of several tens of micrometers. The nanorings and the short and long nanotubes were able to encapsulate proteins and thereby suppress aggregation induced by thermal denaturation. In addition, the nanotubes accelerated refolding of denatured proteins by encapsulating them and then releasing them into the bulk solution; refolding occurred simultaneously with release. In contrast, the nanorings did not accelerate protein refolding. Refolding efficiency increased with increasing nanotube length, indicating that the re-aggregation of the proteins was strictly inhibited by lowering the concentration of the proteins in the bulk solution as the result of the slow release from the longer nanotubes. The migration of the proteins through the long, narrow nanochannels during the release process will also contribute to refolding.