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The conversion of toxic Fe2+ into non-toxic Fe3+ stored in the inner cavity of ferritin nanocage could effectively reduce the occurrence of the Fenton reaction and inhibit the formation of harmful reactive oxygen species (ROS). In this study, we reveal that oyster ferritin (GF1) can rely on its high catalytic activity (7.7 times that of rHuHF) and high binding ability of Fe2+ (9.1 times that of rHuHF) to reduce the precursors of Fenton reaction, thus inhibiting the occurrence of Fenton reaction and slowing down reactive oxygen species-mediated inflammation. The above significant advantage of GF1 can be attributed to the Asp at the position 120th, which could increase the negatively charged area of three-fold channels from 37.8% (rHuHF) to 67.8% and then enhance its oxidation rate and ability of GF1. The findings are of great value in advancing novel nanoparticle drug design based on crystalline structure. [Display omitted] • Asp120 of oyster ferritin had a contribution to the catalytic oxidation rate of Fe2+. • Oyster ferritin shows the catalytic activity of 7.7 times higher than that of rHuHF. • Oyster ferritin shows the binding ability of 9.1 times higher than that of rHuHF. • Oyster ferritin could significantly reduce the precursors of Fenton reaction. [ABSTRACT FROM AUTHOR]

The inter-subunit interaction at the protein interfaces plays a key role in protein self-assembly, through which enabling protein self-assembly controllable is of great importance for preparing the novel nanoscale protein materials with unexplored properties. Different from normal 24-meric ferritin, archaeal ferritin, Thermotoga maritima ferritin (TmFtn) naturally occurs as a dimer, which can assemble into a 24-mer nanocage induced by salts. However, the regulation mechanism of protein self-assembly underlying this phenomenon remains unclear. Here, a combination of the computational energy simulation and key interface reconstruction revealed that a short helix involved interactions at the C 4 interface are mainly responsible for the existence of such dimer. Agreeing with this idea, deletion of such short helix of each subunit triggers it to be a stable dimer, which losses the ability to reassemble into 24-meric ferritin in the presence of salts in solution. Further support for this idea comes from the observation that grafting a small helix from human H ferritin onto archaeal subunit resulted in a stable 24-mer protein nanocage even in the absence of salts. Thus, these findings demonstrate that adjusting the interactions at the protein interfaces appears to be a facile, effective approach to control subunit assembly into different protein architectures. [Display omitted] • Computational analyses reveal the energy difference between HuHF and TmFtn. • A short helix is crucial for TmFtn assembly from dimer to 24-mer. • Deletion of the short helix makes TmFtn only stay in its dimeric form. • Grafting E -helix of HuHF onto TmFtn enables it to only stay in its 24meric form. [ABSTRACT FROM AUTHOR]

As a typical bioactive compound from the bark and leaves of the trees of the genus Cinnamomum, cinnamaldehyde (CIN) is natural and safe. Its excellent antibacterial activity against various foodborne microorganisms is growingly regarded as a promising additive for improving and enhancing the properties of bio-based packaging films/coatings. This review systematically summarized the bio-based food packaging films/coatings containing CIN developed recently. The effects of CIN incorporation on physical and chemical properties of the antibacterial food packaging films/coatings, including thickness, color index, transparency, water content, water solubility, water contact angle, mechanical performances, water barrier performances, and antibacterial performances, were discussed. Simultaneously, this work also concluded that an explanation of the antibacterial mechanism of CIN and preparation methods of bio-based packaging films/coatings containing CIN/CIN carriers. Notably, the incorporation of CIN into the films/coatings could enhance their antibacterial performance extend the shelf-life of various foods, such as fish, meats, vegetables, fruits, and other perishable food, while improving their physical and chemical properties. Although incorporating CIN into food packaging films/coatings has been extensively studied, long-term follow-up research on the human safety of active food packaging films/coatings containing CIN needs to be carried out. [ABSTRACT FROM AUTHOR]

Ferritin is a class of naturally occurring iron storage proteins, which is distributed widely in animal, plant, and bacteria. It usually consists of 24 subunits that form a hollow protein shell with high symmetry. One holoferritin molecule can store up to 4500 iron atom within its inner cavity, and it becomes apoferritin upon removal of iron from the cavity. Recently, scientists have subverted these nature functions and used reversibly self-assembled property of apoferritin cage controlled by pH for the encapsulation and delivery of bioactive nutrients or anticancer drug. In all these cases, the ferritin cages shield their cargo from the influence of external conditions and provide a controlled microenvironment. More importantly, upon encapsulation, ferritin shell greatly improved the water solubility, thermal stability, photostability, and cellular uptake activity of these small bioactive compounds. This review aims to highlight recent advances in applications of ferritin cage as a novel vehicle in the field of food science and nutrition. Future outlooks are highlighted with the aim to suggest a research line to follow for further studies. [ABSTRACT FROM AUTHOR]

Protein assemblies with high symmetry are widely distributed in nature. Most efforts so far have focused on repurposing these protein assemblies, a strategy that is ultimately limited by the structures available. To overcome this limitation, methods for fabricating novel self-assembling proteins have received intensive interest. Herein, by reengineering the key subunit interfaces of native 24-mer protein cage with octahedral symmetry through amino acid residues insertion, we fabricated a 16-mer lenticular nanocage whose structure is unique among all known protein cages. This newly non-native protein can be used for encapsulation of bioactive compounds and exhibits high uptake efficiency by cancer cells. More importantly, the above strategy could be applied to other naturally occurring protein assemblies with high symmetry, leading to the generation of new proteins with unexplored functions. [ABSTRACT FROM AUTHOR]

Protein assemblies with high symmetry are widely distributed in nature. Most efforts so far have focused on repurposing these protein assemblies, a strategy that is ultimately limited by the structures available. To overcome this limitation, methods for fabricating novel self-assembling proteins have received intensive interest. Herein, by reengineering the key subunit interfaces of native 24-mer protein cage with octahedral symmetry through amino acid residues insertion, we fabricated a 16-mer lenticular nanocage whose structure is unique among all known protein cages. This newly non-native protein can be used for encapsulation of bioactive compounds and exhibits high uptake efficiency by cancer cells. More importantly, the above strategy could be applied to other naturally occurring protein assemblies with high symmetry, leading to the generation of new proteins with unexplored functions. [ABSTRACT FROM AUTHOR]

Onion and garlic are two important vegetables in the world, which are processed in various forms such as powder, puree, and minced paste. During processing, discoloration is a major concern because it limits commercial utilization. Recently, the mechanism of the discoloration has gained a particular scientific interest, and a great progress has been made in this field. It is concluded that a greater knowledge of these areas would lend to the development of more efficient methods of controlling the discoloration. Future outlooks are highlighted with the aim to suggest a research line to follow for further studies. [Copyright &y& Elsevier]

Although apoferritin has been widely utilized as a new class of natural protein nanovehicles for encapsulation and delivery of nutraceuticals, its ability to remove metal heavy ions has yet to be explored. In this study, for the first time, we demonstrated that the ferritin from kuruma prawns (Marsupenaeus japonicus), named MjF, has a pronouncedly larger ability to resist denaturation induced by Cd2+ and Hg2+ as compared to its analogue, human H-chain ferritin (HuHF), despite the fact that these two proteins share a high similarity in protein structure. Treatment of HuHF with Cd2+ or Hg2+ at a metal ion/protein shell ratio of 100/1 resulted in marked protein aggregation, while the MjF solution was kept constantly clear upon treatment with Cd2+ and Hg2+ at different protein shell/metal ion ratios (50/1, 100/1, 250/1, 500/1, 1000/1, and 2500/1). Structural comparison analyses in conjunction with the newly solved crystal structure of the complex of MjF plus Cd2+ or Hg2+ revealed that cysteine (Cys) is a major residue responsible for such binding, and that the large difference in the ability to resist denaturation induced by these two heavy metal ions between MjF and HuHF is mainly derived from the different positions of Cys residues in these two proteins; namely, Cys residues in HuHF are located on the outer surface, while Cys residues from MjF are buried within the protein shell. All of these findings raise the high possibility that prawn ferritin, as a food-derived protein, could be developed into a novel bio-template to remove heavy metal ions from contaminated food systems. [ABSTRACT FROM AUTHOR]

Summary Vitamin A (VA) is a fat‐soluble compound that is essential for physiological functions including vision, fetal growth, immune response, cell differentiation and proliferation. However, its susceptibility to environmental conditions leading to poor stability limits its application in food. This study investigated the interaction between egg white protein (EWP) and VA by spectroscopy and molecular docking. The results indicated one EWP could bind 16.00 ± 0.89 VA molecules and the binding constant is (2.59 ± 0.71) × 105 m−1. What's more, there was a fluorescence resonance energy transfer between EWP and VA, and the Förster radius is 5.28 nm. In addition, VA enhanced the hydrophobic interactions with the EWP, resulting in protein aggregation, larger average particle size and more uniform particle size distribution. Finally, the combination of VA with EWP could significantly improve the photothermal stability and storage stability of VA. These studies indicate that EWP nanocomplexes can be used as ideal delivery carriers for bioactive substances. [ABSTRACT FROM AUTHOR]

Dried abalones are precious products, in which candy abalone is the most treasured one, owing to its unique taste. After rehydration and simmering, the core part tastes extraordinarily tender and viscoelastic, just like a soft candy which may almost melt in mouth. However, the reason for this has yet to be elucidated. The purpose of this study is to research the formation mechanism of the candy-like core in candy abalone. First of all, we characterized the viscoelasticity, microstructure and protein changes of candy abalone during the simmering process. The texture results indicated that the springiness and adhesiveness of candy abalone showed an increase. Scanning and transmission electron microscopy suggested that myofibrillar protein in candy abalone formed a dense three-dimensional network hydrogel structure. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis revealed such a hydrogel structure might be derived from the degradation of the myofibrillar protein during the drying process. Also, we identified degraded peptides mainly stemmed from paramyosin by mass spectrometry. Moreover, molecular dynamics simulation revealed that the hydrogen bonds and hydrophobic interactions are mainly responsible for the self-assembly of peptides during the rehydration and simmering stages. Different from reported protein hydrogels, the rheological and morphological properties of the formed peptide hydrogels in candy abalone have significant changes. In this study, we found that the myofibrillar protein of fresh abalone degraded into peptides during the drying process, which further cross-linked to form a peptide hydrogel during the rehydration and simmering stages, thereby producing a unique viscoelastic candy-like core in candy abalone. [ABSTRACT FROM AUTHOR]

Heavy metal ions pollution can cause damage to human body through food, so the development of a new kind of macromolecular that can remove heavy metal ions damage has a good application prospect. The possibilities of removing heavy metal ions from food system with ferritin were studied in this paper. In this study, oyster ferritin (GF1) can resistant to denaturation induced by Pb2+, Cd2+, Cr3+ and still maintains its basic structure. GF1 can bind more Pb2+, Cd2+, Cr3+ than recombinant human H-chain ferritin (rHuHF), especially Pb2+, and the findings suggest that each GF1 can capture about 51.42 Pb2+ in solution. The hard and soft acids and base also verifies that Pb2+ have stronger binding ability to the key amino acids at the outer end of the three-fold symmetry channel. Cells preprotected by ferritin could resistant to heavy metal ions. And GF1 can reduce the high blood lead in mice and may play a role in alleviating lead poisoning in vivo. All findings demonstrated that GF1 can be used as a novel macromolecule to bind heavy metal ions, and the study can broaden the research scope of ferritin in contaminated food systems. [Display omitted] • Oyster ferritin can maintain certain structural and physiological activities upon treatment with Pb2+, Cd2+ and Cr3+. • Oyster ferritin can bind more Pb2+ than recombination human heavy chain ferritin. • Oyster ferritin can significantly reduced blood lead levels in mice. [ABSTRACT FROM AUTHOR]

Summary: Phytoproteins have been widely implemented in the food industry benefiting from their good functionalities, vast reserves and relatively low cost. However, phytoproteins frequently experience poor solubility, which limits their applications. In our study, the solubility of soy protein isolate (SPI) treated with pH‐shifting increased over 1.8 times; however, the transglutaminase‐induced gel properties were sacrificed. To solve this problem, walnut protein (WP) was used to co‐assemble with SPI during the treatment. The co‐assembly hybrid protein shows significantly better solubility, meanwhile, maintaining the transglutaminase‐induced gel properties and improving the cohesiveness and resilience properties compared with untreated SPI, which behaved an improved water holding capacity during storage. The detailed mechanisms were investigated with rheological analysis, SEM, textural analysis and Fourier transform infrared spectroscopy (FTIR). Overall, our study provided a promising strategy to develop SPI/WP hybrid composites with high solubility and improved gel properties to extend the application of SPI in the food industry. [ABSTRACT FROM AUTHOR]

Ferritin can form nanocage architectures and has demonstrated potential to serve as functional nanomaterials. Here, the oyster (Crassostrea gigas) ferritin gene GF1 was obtained from the viscera of the oyster, successfully cloned, prokaryotically expressed in E. coli BL21 (DE3), purified and characterized. Oyster ferritin was purified by ion exchange chromatography using DEAE-Sepharose Fast Flow. The molecular weight of the subunit was 19972 Da (polyacrylamide gel electrophoresis), and the oyster ferritin weight was 480 kDa (non-denaturing gel electrophoresis). After in-gel trypsin digestion, ferritin was identified using NanoLC-Q-TOF-MS and then analyzed by circular dichroism (CD) spectrometry for its secondary structure. Ferritin nanocages were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The three-dimensional structure of oyster ferritin was constructed based on the amino acid sequence of human ferritin heavy chain by the homology modeling method. Here, we provide a theoretical foundation for ferritin self-assembly and biological functional activity. Image 1 • The recombinant oyster ferritin was firstly purified and characterized. • Oyster ferritin 24 subunits can self-assemble into spherical shells. • The three-dimensional structure of subunit and spherical shell was reported. [ABSTRACT FROM AUTHOR]

Background: Protein nanocages have emerged as popular nanocarriers for either drug delivery or biotemplates for the preparation of nanomaterials. However, only three interfaces, namely exterior surface, intersubunit and inner cavity, have been used as reaction sites for the above purposes with all known protein nanocages. On the other hand, how to control the site of Au NCs formed within a targeted protein template while maintaining the functionality of protein itself remains challenging. Results: In this work, inspired by compartmentalization in living systems, we firstly come up with the conception of "intrasubunit interfaces", located within subunit of protein nanocage. We built a new, specific compartment for fabrication of gold nanoclusters by genetic modification of the inherent ferroxidase center located within four-α-helix bundle of each ferritin subunit. This newly built compartment not only realizes the site-directed synthesis of gold nanoclusters but also has no effect on the functionality of ferritin itself such as encapsulation by its inner cavity. These redesigned composites can be further applied as fluorescent imaging agent and carriers for preparation of hybrid nanomaterials. Conclusions: The designing strategy of intrasubunit interfaces opens a new way for future applications of cage-like proteins. [ABSTRACT FROM AUTHOR]

The favorable physicochemical properties are essential for the application of protein-based nanovehicles in the field of biomaterials. Herein, we found that the thermal stability of Marsupenaeus japonicus ferritin (MjFer) (T m = 109.1 ± 0.4 °C) is markedly higher than human H-chain ferritin (HuHF) (T m = 87.7 ± 0.3 °C), although they share a high structural similarity. Multiple results indicated that the promoted thermal stability of MjFer is mainly derived from the salt bridges located at the C 3 interface. Consequently, MjFer exhibits strong protective effects on encapsulated curcumin upon exposure at high temperatures. In contrast, most of the curcumin loaded HuHF composites precipitated rapidly under the same conditions. These findings elucidated the molecular mechanism of the hyperthermostability of MjFer and illustrated that MjFer could act as a robust insulation nanocarrier for bioactive compounds against various thermal treatments. [ABSTRACT FROM AUTHOR]

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]

Protein nanocages have recently received considerable attention in the fields of nanoscience and nanomedicine and have been used as either biotemplates for the preparation of a variety of nanomaterials or vehicles for drugs or imaging agents. However, their utilization for detection of heavy metal ions has yet to be explored. In this study, by grafting a mercury binding peptide (MBP) on the exterior surface of a recombinant human H-chain ferritin (rHuHF) nanocage, we successfully prepared a new protein nanocage (HuHF-MBP) which exhibits high binding capacity and affinity for Hg2+. The fluorescence of HuHF-MBP labeled with a green fluorescent dye fluorescein isothiocyanate (FITC) can be quenched by graphene oxide (GO), while addition of Hg2+ to the above solution recovered the quenched fluorescence in a dose-dependent manner. Thus, this system consisting of FITC-labeled HuHF-MBP and GO, where FITC and graphene oxide were used as fluorescent reporter probes, has great potential to be explored as a sensor for Hg2+ detection. Indeed, this newly constructed protein sensor exhibited high sensitivity and selectivity for Hg2+, and the limit of detection was 1.0 nM. The construction of this system provides an alternative strategy for the preparation of heavy metal ion sensors by using protein nanocages as biotemplates. [ABSTRACT FROM AUTHOR]

As the second most abundant trace element in the human body, zinc nutrition is constantly a hot topic. More than one-third population is suffering zinc deficiency, which results in various types of diseases or nutritional deficiencies. Traditional ways of zinc supplementation seem with low absorption rates and significant side effects. Zinc supplements with dietary components are easily accessible and improve zinc utilization rate significantly. Also, mechanisms of maintaining zinc homeostasis are of broad interest. The present review focuses on zinc nutrition in human health in inductive methods. Mainly elaborate on different diseases relating to zinc disorder, highlighting the impact on the immune system and the recent COVID-19. Then raise food-derived zinc-binding compounds, including protein, peptide, polysaccharide, and polyphenol, and also analyze their possibilities to serve as zinc complementary. Finally, illustrate the way to maintain zinc homeostasis and the corresponding mechanisms. The review provides data information for maintaining zinc homeostasis with the food-derived matrix. [ABSTRACT FROM AUTHOR]

Ferritin is an important iron storage protein, which is widely existed in all forms of life. Ferritin can regulate iron homeostasis when iron ions are lacking or enriched in the body, so as to avoid iron deficiency diseases and iron poisoning. Ferritin presents a hollow nanocage, which can store ions or other small molecular substances in the cavity. Therefore, ferritin shows its potential as a functional nanomaterial that can deliver nutrients or drugs in a targeted manner to improve bioavailability. Due to the special structure, the research on ferritin has attracted more and more attention in recent years. In this paper, the structural characteristics of ferritin were introduced, and the natural purification and prokaryotic expression methods of ferritin from different sources were described. At the same time, ferritin can bind to small molecules, so that it has the activity of small molecules, to construct a new type of ferritin. As a result, ferritin plays an important role as a nutrient substance, in targeted transport, and disease monitoring, etc. In conclusion, the yield of ferritin can be improved by means of molecular biology. Meanwhile, molecular modification can be used to make ferritin have unique activity and function, which lays a foundation for subsequent research. The molecular and structural properties of ferritins were clearly described. Isolation and purification technologies of ferritin were compared. Characterization, functions and molecular modifications mechanism of ferritin were reviewed. The applications of ferritin in pharmaceutical and food industry were prospected. [ABSTRACT FROM AUTHOR]

CO 2 is a greenhouse gas and a major contributor to global warming. Efficient conversion of CO 2 into high value-added food materials represents a promising strategy to decrease CO 2 concentration. In this study, we reported that Ca2+-crosslinked alginate beads loaded with carbonic anhydrase (CA) can efficiently catalyze conversion of CO 2 into porous vaterite CaCO 3 particles via a carboxymethyl cellulose (CMC) inducing process. CA encapsulated within the Ca2+-crosslinked alginate beads maintained around 100% activity of its original activity after 10 assay cycles. Functionally, the CA-loaded alginate beads facilitated conversion of CO 2 into porous vaterite CaCO 3 particles with high CO 2 removal efficiency in the presence of carboxymethyl cellulose. Notably, such vaterite CaCO 3 particles can be explored for adsorption of astaxanthin with higher loading capacity (2.0 wt %), consequently improving the photo- and thermal-stability of this pigment. [Display omitted] • Carbonic anhydrase loaded within alginate beads serves as an edible CO 2 absorber. • These synthesized alginate beads convert CO 2 into vaterite CaCO 3 particles via CMC. • The obtained porous vaterite CaCO 3 particles have high astaxanthin loading capacity. • The vaterite CaCO 3 particles greatly improve the photothermal stability of astaxanthin. [ABSTRACT FROM AUTHOR]

Hemocyanin, an oxygen-transport protein, is widely distributed in the hemolymph of marine arthropods and mollusks, playing an important role in their physiological processes. Recently, hemocyanin has been recognized as a multifunctional glycoprotein involved in the immunological responses of aquatic invertebrates. Consequently, the link between hemocyanin functions and their potential applications has garnered increased attention. This review offers an integrated overview of hemocyanin's structure, physicochemical characteristics, and bioactivities to further promote the utilization of hemocyanin derived from marine products. Specifically, we review its implication in two aspects of food and aquaculture industries: quality and health. Hemocyanin's inducible phenoloxidase activity is thought to be an inducer of melanosis in crustaceans. New anti-melanosis agents targeted to hemocyanin need to be explored. The red-color change observed in shrimp shells is related to hemocyanin, affecting consumer preferences. Hemocyanin's adaptive modification in response to the aquatic environment is available as a biomarker. Additionally, hemocyanin is endowed with bioactivities encompassing anti-microbial, antiviral, and therapeutic activities. Hemocyanin is also a novel allergen and its allergenic features remain incompletely characterized. [Display omitted] [ABSTRACT FROM AUTHOR]

Over the past few decades, 1D self-assembly of proteins into various filaments has received considerable attention. Protein filaments ubiquitously exist in nature, which not only govern the cellar metabolism in vivo but also tune the physiochemical properties of foodstuffs in vitro. Myofibrillar proteins and collagens are natural filaments abundantly occurring in muscles, with a precise associating and dissociating mechanism. Sharing similar morphologies, a great number of globular proteins, sourced from versatile foodstuffs, can likewise be converted into filaments upon different treatments, albeit their structure remains enigmatic. This review summarized both natural and synthetic protein filaments by characterizing their distinct structures, assembly behaviors, methodologies, and promising applications. Finally, current challenges and future strategies in this research field are discussed. The goal of this review is to highlight the essence of different protein filaments constructed by natural and denatured building blocks, which may support valuable insights into food science and broader applications. [Display omitted] • Protein filaments are ubiquitously existed in foodstuffs. • Myofibrillar proteins and collagens have specific assembly mechanism. • Natural and synthesized protein filaments have been compared. • A few factors affect the process of protein fibrilization. [ABSTRACT FROM AUTHOR]

The artificial photoreduction of CO 2 into fuels with precious metal-based photosensitizers such as Ru, Re, and Ir represents a potential way to minimize global warming caused by the growing concentration of CO 2 , but these noble metal-based photosensitizers present unsustainable and negative environmental impact issues, thereby limiting their applications. Herein, bioinspired by the inherent ability of Escherichia coli ferritin (EcBFR) to bind to hemin, we constructed a photocatalytic-CO 2 -conversion platform by using a single shell-like EcBFR molecule where up to 12 of hemin molecules can be incorporated into its intersubunit interfaces as photosensitizers, while the semiconductor photocatalysts nanoferrihydrites are catalytically synthesized and encapsulated within the protein inner cavity. Consequently, the constructed platform can selectively, effectively reduce CO 2 to formic acid with 1-benzyl-1,4-dihydronicotinamide (BNAH) as the electron donor in aqueous solution under mild conditions. To improve the recyclability of the above platform, we designed a three-dimensional (3D) protein crystalline framework with the above constructed hybrid molecules as building blocks through π-π interactions. Notably, such protein framework enables the recyclability to be improved up to at least 5 cycles as compared to the individual protein nanocage. All these findings pave the way for CO 2 photoreduction by naturally occurring heme as the photosensitizer in an environmentally friendly manner. [Display omitted] • Escherichia coli ferritin (EcBFR) was explored as a CO 2 photocatalytic platform. • The photosensitizer hemin and biocatalyst ferrihydrite were integrated into a single protein nanocage for CO 2 photocatalysis. • The constructed photocatalytic platform selectively reduced CO 2 to formic acid. • Designed 3D protein crystalline frameworks facilitate high recyclability. [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]

The low stability of trans‐astaxanthin (AX) not only limits its applications as a functional factor in food systems, but also affects the sensor quality of most shrimp products. Therefore, it is important to find an easy, effective way to improve the physical and chemical stability of AX. In this study, by taking advantage of the co‐existence of AX and shrimp ferritin (Marsupenaeus japonicus ferritin, MjF), we investigated the interaction of AX with MjF. Results showed that AX molecules are able to bind on the outer surface of MjF to form complexes, and quantitative analyses demonstrated that one ferritin molecule is bound to ∼48 AX molecules. Consequently, such binding not only greatly enhances the water solubility, thermal stability, and photo stability of AX, but also protects AX from Fe2+‐induced oxidative damage, as compared to free AX. Thus, MjF could be used as a protective molecule to improve the physical and chemical stability of AX. Practical Application: Our study opens up a new avenue for improving the physicochemical properties of bioactive molecules by interacting with protein, and shrimp ferritin could be explored as a protective system for the bioactive molecules. [ABSTRACT FROM AUTHOR]

Compartmentalization is a hallmark of living systems. Through compartmentalization, ubiquitous protein nanocages such as viral capsids, ferritin, small heat shock proteins, and DNA-binding proteins from starved cells fulfill a variety of functions, while their shell-like structures hold great promise for various applications in the field of nanomedicine and nanotechnology. However, the number and structure of natural protein nanocages are limited, and these natural protein nanocages may not be suited for a given application, which might impede their further application as nanovehicles, biotemplates or building blocks. To overcome these shortcomings, different strategies have been developed by scientists to construct artificial protein nanocages, and 1D, 2D and 3D protein arrays with protein nanocages as building blocks through genetic and chemical modification to rival the size and functionality of natural protein nanocages. This review outlines the recent advances in the field of the design and construction of artificial protein nanocages and their assemblies with higher order, summarizes the strategies for creating the assembly of protein nanocages from zero-dimension to three dimensions, and introduces their corresponding applications in the preparation of nanomaterials, electrochemistry, and drug delivery. The review will highlight the roles of both the inter-subunit/intermolecular interactions at the key interface and the protein symmetry in constructing and controlling protein nanocage assemblies with different dimensions. [ABSTRACT FROM AUTHOR]

Lead can induce oxidative stress and increase lipid peroxidation in biofilms, leading to liver damage and physiological dysfunction. This study aimed to investigate how oyster ferritin (GF1) attenuates lead-induced oxidative damage to the liver in vitro and in vivo. Animal experiments have confirmed that lead exposure can lead to oxidative damage and lipid peroxidation of the liver, and ferritin can regulate the activity of antioxidant enzymes and alleviate pathological changes in the liver. At the same time, oyster ferritin can regulate the expression of oxidative stress-related genes and reduce the expression of inflammasome-related genes. In addition, lead can induce apoptosis and mitophagy, leading to overproduction of reactive oxygen species and cell death, which can be effectively alleviated by oyster ferritin. Overall, this study provides a theoretical foundation for the use of oyster ferritin as a means of mitigating and preventing lead-induced damage. • Oyster can regulate the activity of antioxidant enzymes and alleviate pathological changes in the liver. • Oyster ferritin can regulate the expression of oxidative stress-related genes and inflammasome-related genes. • Oyster ferritin can effectively alleviate lead-induced apoptosis and mitochondrial autophagy in LO2 cells. [ABSTRACT FROM AUTHOR]

• Protein hydrogel was constructed with native paramyosin and natural crosslinkers. • PM hydrogels show an injectable and reversible characteristic. • PM gelation trigged by different crosslinkers show various rheological properties. • C3G photostability improved upon its encapsulation within the PM hydrogel. • PM hydrogels could effectively expedite wound healing of the skin in mice. Protein hydrogels with multifunction including tunable mechanical property, sustained drug release and excellent biocompatibility have shown considerable promise in biological applications. However, these hydrogels are usually generated using denatured or modified protein molecules, it remains challenging to construct injectable hydrogel based on native protein as building blocks. Here, a native nanofibrous protein, paramyosin (PM) was utilized as building blocks to create hydrogels under mild conditions, taking advantage of Zn2+-mediated metal coordination with His-Glu motifs located on the exterior surface of the protein. The bioactive substance cyanidin-3- O -galactoside was shielded from light-induced degradation by being enclosed in the native PM hydrogels. Moreover, the rheological property and biological activity of construction PM hydrogels were improved through noncovalent interactions with natural polyphenols, such as proanthocyanidins. Importantly, all of these manufactured native hydrogels endow good biocompatibility, reversible sol–gel transforming behavior, great stability, and considerably speed up the healing of wounds in mice with skin injuries. Overall, these hydrogels derived from natural protein not only demonstrates beneficial qualities that are very effective in encouraging wound healing, but also offers a straightforward and repeatable gelation approach to produce protein hydrogel employed in biomedical applications. [ABSTRACT FROM AUTHOR]

• After adding about 1000 Fe2+ in vitro , oyster ferritin reached the saturation state. • Adding Fe2+ can improve the storage and thermal stability of oyster ferritin. • Heating at 80 ℃ and below does not affect the structure and Fe2+ content of GF1-1000 Fe2+. Ferritin, one of the storage forms of iron, which widely exists in all living organisms and shows its potential as functional nanomaterial. In this study, Fe2+ were added to oyster ferritin (GF1) in vitro until reached experimental saturation state. The structure characterization and monodisperse morphology of ferritin were showed that the protein structure of ferritin did not change significantly after adding Fe2+ and GF1 with 1000 Fe2+ (GF1-1000 Fe2+) was selected for subsequent experiments. The storage stability results showed that 11.27 % of the protein remained cage-like structure when GF1-1000 Fe2+ was stored at 4 °C for 12 days. The thermal treatment results showed that GF1-1000 Fe2+ still maintained certain structure and activity at 80 °C, and 82.8 % of Fe2+ was still retained at 80 °C. These experimental results may provide a theoretical basis for the development of novel iron supplement that are non-toxic and highly stable. [ABSTRACT FROM AUTHOR]

[Display omitted] • The low stability of astaxanthin limits its application as a bioactive factor. • Algae, fish and crustaceans in nature stabilize astaxanthin by binding to proteins. • Structure and physicochemical properties of proteins affect its binding capacity. • Conformational changes of astaxanthin in protein complex cause species color changes. • Inspiration from nature provides advanced strategies for utilization of astaxanthin. The pigment astaxanthin, one of the carotenoids, is regarded as a functional factor with various biological activities, widely applied in feed, nutraceutical, and cosmetic industries. However, its low stability and poor water solubility limit its application. Examples in nature suggest that binding to proteins is a simple and effective method to improve the stability and bioavailability of astaxanthin. Proteins from algae, fish, and crustaceans have all been demonstrated to have astaxanthin-binding capacity. Inspired by nature, artificial astaxanthin-protein systems have been established in foods. Binding to proteins could bring aquatic species various colors, and changes in the conformation of astaxanthin after binding to proteins leads to color changes. The review innovatively summarizes multiple examples of proteins as means of protecting astaxanthin, giving a reference for exploring and analyzing pigment-protein interactions and providing a strategy for carotenoids stabilization and color regulation, which is beneficial to the broader and deeper applications of carotenoids. [ABSTRACT FROM AUTHOR]

Cyclic adenosine monophosphate (cAMP) has received considerable attention because it naturally occurs in jujube fruit and possesses many activities such as antitumor activity. However, its poor membrane permeability limits its applications in food industry. In this study, we found that polysaccharides likewise derived from jujube (ZJP) are able to increase the membrane permeability of cAMP for the first time. To elucidate the mechanism, the interactions of cAMP and ZJP were determined by spectroscopic, thermodynamic and molecular docking methods. Results showed that acidic polysaccharide (ZJPA) owned a stronger affinity to cAMP as compared to neutral polysaccharide (ZJPN). Consequently, the binding of ZJPA to cAMP existed a better synergistic antioxidant capacity and also protected ZJPA against pH-induced degradation. More importantly, the formed ZJPA-cAMP complexes exhibited much better bio-accessibility than unbound cAMP as was approved by Caco-2 cell absorption experiment. These new findings are beneficial for designing polysaccharide-based nanocarriers for cAMP. [Display omitted] • Jujube polysaccharides do bind to cyclic adenosine monophosphate. • Acidic polysaccharides bind to cyclic adenosine monophosphate more strongly. • Charge interaction, H-bonding and hydrophobic effect contribute to binding. • Cyclic adenosine monophosphate enhances bioactivity of Polysaccharides. • Polysaccharides promote absorption of cyclic adenosine monophosphate by Caco-2 cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • ApF exhibits better DNA protection activity than MjF. • The higher DNA-protective ability of ApF stems from its higher ferroxidase activity. • Crystal structure of ApF was resolved for the first time at a resolution of 2.4 Å. • Difference in ferroxidase activity comes from structural difference of ApF and MjF. The structure and function of ferritin from seafood has been largely unexplored. In this study, homopolymeric scallop ferritin (ApF) was prepared for the first time, the apo form of which exhibited the stronger ability to protect DNA from iron-induced oxidative damage as compared to its analogue, homopolymeric shrimp ferritin (MjF). Their difference in DNA-protective activity was derived from less hydroxyl radicals produced during iron oxidation in the presence of scallop ferritin than shrimp ferritin. The kinetic results showed that apo-ApF catalyzed the faster ferrous ions oxidation by oxygen into nontoxic ferric ions as compared to apo-MjF. Newly reported crystal structure of ApF revealed that its stronger ferroxidase activity stemmed from different structures in the triple axis channel and ferroxidase site as compared to MjF. All these new findings advance our understanding of the relationship between the structure and function of food-related protein. [ABSTRACT FROM AUTHOR]

Highlights: [•] β-Carotene can be encapsulated within ferritin shell. [•] The β-carotene-containing ferritin nanocomposites become water-soluble. [•] Such encapsulation improves the thermal stability of β-carotene. [ABSTRACT FROM AUTHOR]

• Point mutation in D120G could improve the thermal stability of oyster ferritin. • The spherical shell of mutated ferritin can be kept well at 90 °C and below. • The stability of oyster ferritin was promoted via the improved 3-fold interfaces. Ferritin can be widely used as functional nanomaterial. But the physiological activity of ferritin can be damaged under excessive temperatures, which affect the self-assembly property. In this study, point mutation was produced in Asp120 to Gly120 of ferritin amino acid sequence and the heat resistance was improved significantly. The thermal denaturation temperature of mutated ferritin is 89.17 °C and has increased by 13 °C more than the wild-type oyster ferritin. The effect of thermal treatment on the denaturation, aggregation state, particle size and the structure of ferritin was not changed before 90 °C. The computational modeling and analysis indicated that mutated ferritin promotes the overall structural stability assembly via decreasing the interaction energies of 62 percent energies in 3-fold interface. Improving the thermal stability of oyster ferritin by point mutation enhances its applications as a food ingredient. [ABSTRACT FROM AUTHOR]

Histidine (His) residues represent versatile motifs for designing protein-protein interactions because the protonation state of the imidazole group of His is the only moiety in protein to be significantly pH dependent under physiological conditions. Here we show that, by the designed His motifs nearby the C4 axes, ferritin nanocages arrange in crystals with a simple cubic stacking pattern. The X-ray crystal structures obtained at pH 4.0, 7.0, and 9.0 in conjunction with thermostability analyses reveal the strength of the π–π interactions between two adjacent protein nanocages can be fine-tuned by pH. By using the crystal structural information as a guide, we constructed 3D protein frameworks in solution by a combination of the relatively weak His–His interaction and Ni2+-participated metal coordination with Glu residues from two adjacent protein nanocages. These findings open up a new way of organizing protein building blocks into 3D protein crystalline frameworks. Controlling protein–protein interactions through non-covalent bonding is desirable for the assembly of protein arrays. Here the authors demonstrate that pH-tunable π–π stacking interactions between Histidine motifs can direct the assembly of 3D protein arrays. [ABSTRACT FROM AUTHOR]

• Thermal treatment could induce denaturation and aggregation of oyster ferritin. • The ferritin spherical shell destroyed gradually and could not be observed at 100 °C. • Thermal treatment could change the structure of oyster ferritin. The unique nanocage structure of ferritin can be used as functional nanomaterials and has wide application prospects. However, thermal treatment may affect the structure of ferritin, further affecting self-assembly property. In this study, the oyster ferritin gene GF1 was obtained, prokaryotically expressed in E. coli BL21 (DE3). Then the purified ferritin was heated from 60 to 100 °C for 10 min with untreated ferritin as a control sample. The aggregation state of ferritin was investigated and the difference in protein structure was evaluated in terms of particle size and protein structures. The results of electrophoresis indicated that thermal treatment induced denaturation and aggregation of ferritin macromolecules. Moreover, the particle size distribution shifted to larger size trend and aggregates were visible with the heated samples and the secondary structure and tertiary structure were destroyed gradually. The findings are beneficial for understanding the relationship of the structure and function of ferritin. [ABSTRACT FROM AUTHOR]