Protein Glue Research Articles

The intrinsically disordered protein glue of the myelin major dense line: Linking AlphaFold2 predictions to experimental data

Numerous human proteins are classified as intrinsically disordered proteins (IDPs). Due to their physicochemical properties, high-resolution structural information about IDPs is generally lacking. On the other hand, IDPs are known to adopt local ordered structures upon interactions with e.g. other proteins or lipid membrane surfaces. While recent developments in protein structure prediction have been revolutionary, their impact on IDP research at high resolution remains limited. We took a specific example of two myelin-specific IDPs, the myelin basic protein (MBP) and the cytoplasmic domain of myelin protein zero (P0ct). Both of these IDPs are crucial for normal nervous system development and function, and while they are disordered in solution, upon membrane binding, they partially fold into helices, being embedded into the lipid membrane. We carried out AlphaFold2 predictions of both proteins and analysed the models in light of experimental data related to protein structure and molecular interactions. We observe that the predicted models have helical segments that closely correspond to the membrane-binding sites on both proteins. We furthermore analyse the fits of the models to synchrotron-based X-ray scattering and circular dichroism data from the same IDPs. The models are likely to represent the membrane-bound state of both MBP and P0ct, rather than the conformation in solution. Artificial intelligence-based models of IDPs appear to provide information on the ligand-bound state of these proteins, instead of the conformers dominating free in solution. We further discuss the implications of the predictions for mammalian nervous system myelination and their relevance to understanding disease aspects of these IDPs.

Molecularly Engineered Protein Glues with Superior Adhesion Performance.

Naturally inspired proteins are investigated for the development of bioglues that combine adhesion performance and biocompatibility for biomedical applications. However, engineering such adhesives by rational design of the proteins at the molecular level is rarely reported. Herein, it is shown that a new generation of protein-based glues is generated by supramolecular assembly through de novo designed structural proteins in which arginine triggers robust liquid-liquid phase separation. The encoded arginine moieties significantly strengthen multiple molecular interactions in the complex, leading to ultrastrong adhesion on various surfaces, outperforming many chemically reacted and biomimetic glues. Such adhesive materials enable quick visceral hemostasis in 10 s and outstanding tissue regeneration due to their robust adhesion, good biocompatibility, and superior antibacterial capacity. Remarkably, their minimum inhibitory concentrations are orders of magnitude lower than clinical antibiotics. These advances offer insights into molecular engineering of de novo designed protein glues and outline a general strategy to fabricate mechanically strong protein-based materials for surgical applications.

The chemistry behind the first Portuguese postage stamps (1853–1894). A non-destructive analytical and chemometric analysis of pigments, fillers and binders

The analysis of 28 specimens of some of the first Portuguese postage stamps, dated from 1853 to 1894, was undertaken with non-destructive techniques: X-Ray fluorescence (XRF), Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Ultraviolet–Visible Reflectance Spectroscopy (UV–Vis). Ink, paper and cancellation of the postage stamps were analysed, and the pigments, binders and fillers identified. Prussian blue was found present in all blue and also in green and brown specimens. Chrome and zinc yellow, lead sulphate and mars red were also found in other of the investigated postage stamps. Binders consist mostly of protein glue. Fillers such as calcite and kaolinite were found dominant. The presence of the latter served as an indicator for distinguishing between genuine and forged samples. UV–Vis spectra also proved useful for the same purpose. All the above information was processed and organized using chemometric techniques. These include mainly Hierarchical Cluster Analysis (HCA), for clustering stamps of similar composition, and Principal Component Analysis (PCA) for mapping the samples and identifying the more relevant variables. The latter are, in the paper, content of calcium, potassium, sulphur and silicon and, in the dye pigment area, of iron, zinc and lead content. The study introduces an approach in which, by combination of non-destructive multi analytical techniques with chemometric analysis, extensive information on different aspects of the composition of the studied postage stamps is provided, including that of paper and dyes.

CT-US fusion imaging increases the feasibility of early ultrasound-guided percutaneous intervention of local drug therapy in pancreatic contusion and laceration.

BackgroundMultimodal fusion imaging (MMFI) was usually used to assist percutaneous procedures for difficult lesions, with most applications occurring with hepatic and prostatic interventions. This paper aimed to evaluate the precision and effectiveness of computed tomography-ultrasound (CT-US) fusion imaging (CUFI)-assisted US-guided percutaneous intervention (UGPI) in early local drug therapy for pancreatic contusion and laceration (PCL).MethodsA total of 12 pigs with PCL were randomly divided into a CUFI-assisted UGPI (MU) group (n=6) and a single UGPI (SU) group (n=6). The MU group underwent CUFI-assisted UGPI of locally applied medical protein glue (1 mL) injection while the SU group received the same therapy using two-dimensional UGPI. The duration and accuracy of each procedure were observed in the 2 groups.ResultsIn the MU group, the overall time of the procedure for locking the plane was 1.85±0.06 minutes. Less time was spent in the selection of the pathway and puncture site in the MU group compared with the SU group (6.56±0.42 vs. 7.61±0.44 minutes, P<0.01). The duration of puncturing and drug injection was also shorter in the MU group than in the SU group (3.41±0.30 vs. 4.20±0.20 minutes, P<0.01) and the MU group had a higher accuracy of medical protein glue injection than the SU group (100% vs. 50%, P<0.05).ConclusionsCUFI could increase the precision and effectiveness of early UGPI in the delivery of local drug therapy in PCL.

Wooden nacre is strong and tough

Drawing inspiration from mother-of-pearl, or nacre—a strong, natural material that lines some mollusk shells—researchers have turned wood waste into a sturdy building material (ACS Nano 2020, DOI: 10.1021/acsnano.9b08647). Nacre’s notable strength and hardness come from brick-like stacks of calcium carbonate held together by protein glue. Qingfeng Sun of Zhejiang A&F University, Huiqiao Li of Huazhong University of Science and Technology, and colleagues aimed to copy the microstructure of nacre to turn wood waste like sawdust into a building material much stronger than standard wooden composites such as particle board. The researchers ground a mixture including wood waste and calcium carbonate, added water to the resulting powder, and heated it to encourage CaCO3 crystals to grow around the wood fibers, mimicking the mineral in natural nacre. The researchers first froze the mix in a mold to create parallel layers of the mineral-and-wood building blocks. They then freeze-dried the material to remove

Processed Food Additive Microbial Transglutaminase and Its Cross-Linked Gliadin Complexes Are Potential Public Health Concerns in Celiac Disease.

Microbial transglutaminase (mTG) is a survival factor for microbes, but yeasts, fungi, and plants also produce transglutaminase. mTG is a cross-linker that is heavily consumed as a protein glue in multiple processed food industries. According to the manufacturers’ claims, microbial transglutaminase and its cross-linked products are safe, i.e., nonallergenic, nonimmunogenic, and nonpathogenic. The regulatory authorities declare it as “generally recognized as safe” for public users. However, scientific observations are accumulating concerning its undesirable effects on human health. Functionally, mTG imitates its family member, tissue transglutaminase, which is the autoantigen of celiac disease. Both these transglutaminases mediate cross-linked complexes, which are immunogenic in celiac patients. The enzyme enhances intestinal permeability, suppresses mechanical (mucus) and immunological (anti phagocytic) enteric protective barriers, stimulates luminal bacterial growth, and augments the uptake of gliadin peptide. mTG and gliadin molecules are cotranscytosed through the enterocytes and deposited subepithelially. Moreover, mucosal dendritic cell surface transglutaminase induces gliadin endocytosis, and the enzyme-treated wheat products are immunoreactive in CD patients. The present review summarizes and updates the potentially detrimental effects of mTG, aiming to stimulate scientific and regulatory debates on its safety, to protect the public from the enzyme’s unwanted effects.

Resizing: A Brief Review of Restoration and Conservation Literature from the 17th to the 21st Century

Abstract From the first half of the seventeenth century until the beginning of the twentieth century resizing was common practice after each aqueous treatment to replace the loss of original sizing, but it is used much less frequently today. As already described in early sources, resizing in modern conservation practice still serves three main purposes: increasing mechanical stability, modifying the surface texture of abraded papers by decreasing their surface roughness and consolidating loosened fibres and preparing the paper substrate for inpainting. Today’s practice, however, differentiates more carefully between an improvement in mechanical stability and increased resistance to physical and chemical degradation processes. While previously almost exclusively protein glues were used for resizing, today gelatine and cellulose ethers are among the most commonly used sizing agents. The solution concentrations used for resizing have significantly decreased: gelatine is used in 0.5 % (w/v) to 1 % (w/v) solutions today, while historic literature recommends 1.6 % (w/v) to 3.5 % (w/v) protein glues. Concerning application techniques, mainly immersion, closely related to tub sizing used during paper manufacture and local or overall brush applications were used for historic sizing. Spraying, which was introduced at the beginning of the second half of the twentieth century, is recommended for resizing drawings to prevent friable media from being smudged.

Supramolecular protein glue to boost enzyme activity

Proteins possess many biological functions. However, they can easily degrade or aggregate, thus losing their bioactivity. Therefore, it is very important to develop materials capable of interacting with proteins and forming nanostructures for protein storage and delivery. In this study, we serendipitously found a novel peptide-based supramolecular protein glue (Nap-GFFYK(γE)2-NH2, compound 1 ) that could co-assemble with proteins into nanofibers and hydrogels. We found that compound 1 rapidly folded into a β-sheet conformation upon contact with many proteins but not with polymers. Total internal reflection fluorescence microscopy (TIRFM) images clearly show the formation of co-assembled nanofibers by proteins and the peptide. The supramolecular protein glue could improve the dispersion of enzymes (lipase and lysozyme) and therefore enhance their catalytic activity, especially at high temperatures. More importantly, the supramolecular protein glue could co-assemble with two enzymes, glucose oxidase/horseradish peroxidase (GOx/HRP) and GOx/cytochrome c (cyt c), to form nanofibers that significantly enhanced the catalytic activity of tandem enzymatic reactions. We envisioned the great potential of our supramolecular protein glue for protein storage, delivery, and bioactivity manipulation.

Early local drug therapy for pancreatic contusion and laceration

ObjectivesTo study the therapeutic effect of early local drug therapy on pancreatic contusion and laceration. MethodsTwenty pigs were divided into 4 groups: model(PL), 1 ml of saline; medical protein glue (EC), 1 ml of medical protein glue; ulinastatin (UL), 50000U of ulinastatin; combined treatment (UE), 1 ml of medical protein glue and 50000U of ulinastatin. 30 min after model establishment, different groups received different local drug treatments. The pancreatic function, peritoneal effusion and pancreatic pathology were observed. ResultsThe UE group got the best therapeutic effect. The changes of pancreatic function and the peritoneal effusion were compared with PL group as follows. 0-6h: amylase (p < 0.01), lipase (p > 0.05), effusion (p < 0.01); 6-12h: amylase (p > 0.05), lipase (p < 0.01), effusion (p < 0.01); 12-24h: amylase (p < 0.01), lipase (p < 0.01), effusion (p < 0.01). ConclusionsEarly local drug therapy in pancreatic contusion and laceration could effectively control the development of the disease and improve the prognosis.

Microbial Transglutaminase is Beneficial to Food Industries but a Caveat to Public Health

Microbial transglutaminase (mTG) is a survival factor for bacteria that is heavily used as a protein glue in the processed food industries. Despite the manufacturers’ claims for it safe usage, scientific observations are accumulating for its unwanted effects on human health. The enzyme can cross link proteins, imitating its family member, tissue transglutaminase, the autoantigen of celiac disease. Its gliadin cross-linked complexes are immunogenic in celiac disease. In the intestinal lumen, mTG exerts anti protease activity and forms resistant isopeptide bonds, it is anti-phagocytic, thus suppressing luminal protective pathways. It increases intestinal permeability, is trans-epithelialy transported and faces the enteric mucosal immune cells. Finally, mTG-containing products can react as emulsifiers and mucolytic agents thus compromising barriers’ integrities. The present review summarizes and updates on the potential detrimental effects of mTG, aiming to protect the public from the enzyme’s unwanted effects.

Unraveling inter-species differences in hagfish slime skein deployment.

Hagfishes defend themselves from fish predators by producing defensive slime consisting of mucous and thread components that interact synergistically with seawater to pose a suffocation risk to their attackers. Deployment of the slime occurs in a fraction of a second and involves hydration of mucous vesicles as well as unraveling of the coiled threads to their full length of ∼150 mm. Previous work showed that unraveling of coiled threads (or 'skeins') in Atlantic hagfish requires vigorous mixing with seawater as well as the presence of mucus, whereas skeins from Pacific hagfish tend to unravel spontaneously in seawater. Here, we explored the mechanisms that underlie these different unraveling modes, and focused on the molecules that make up the skein glue, a material that must be disrupted for unraveling to proceed. We found that Atlantic hagfish skeins are also held together with a protein glue, but compared with Pacific hagfish glue, it is less soluble in seawater. Using SDS-PAGE, we identified several soluble proteins and glycoproteins that are liberated from skeins under conditions that drive unraveling in vitro Peptides generated by mass spectrometry of five of these proteins and glycoproteins mapped strongly to 14 sequences assembled from Pacific hagfish slime gland transcriptomes, with all but one of these sequences possessing homologs in the Atlantic hagfish. Two of these sequences encode unusual acidic proteins that we propose are the structural glycoproteins that make up the skein glue. These sequences have no known homologs in other species and are likely to be unique to hagfishes. Although the ecological significance of the two modes of skein unraveling described here are unknown, they may reflect differences in predation pressure, with selection for faster skein unraveling in the Eptatretus lineage leading to the evolution of a glue that is more soluble.

Microbial Transglutaminase Is Immunogenic and Potentially Pathogenic in Pediatric Celiac Disease.

The enzyme microbial transglutaminase is heavily used in the food processing industries to ameliorate food qualities and elongate the products' shelf life. As a protein's glue, it cross-links gliadin peptides, creating neo-complexes that are immunogenic and potentially pathogenic to celiac disease communities. Even lacking sequence identity, it imitates functionally the endogenous tissue transglutaminase, known to be the autoantigen of celiac disease and representing an undisputable key player in celiac disease initiation and progress. The present review expend on the enzyme characteristics, exogenous intestinal sources, its cross-linking avidity to gluten or gliadin, turning naïve protein to immunogenic ones. Several observation on microbial transglutaminase cross linked complexes immunogenicity in celiac patients are reviewed and its pathogenicity is summarized. Warnings on its potential risks for the gluten dependent conditions are highlighted. When substantiated, it might represent a new environmental factor of celiac disease genesis. It is hoped that the presented knowledge will encourage further research to explore the mechanism and the pathogenic pathways taken by the gliadin cross linked enzyme in driving celiac disease.

Microbial transglutaminase: A new potential player in celiac disease

Microbial transglutaminase is heavily used in the food processing industries to improve food qualities. Being a protein's glue, by cross-linking it creates neoepitope complexes that are immunogenic and potentially pathogenic in celiac disease. Despite low sequence identity, it imitates functionally its family member, the endogenous tissue transglutaminase, which is the autoantigen of celiac disease. The present comprehensive review highlights the enzyme characteristics, endogenous and exogenous intestinal sources, its cross-talks with gluten and gliadin, its immunogenicity and potential pathogenicity and risks for the gluten induced conditions. If substantiated, it might represent a new environmental inducer of celiac disease. The present findings might affect nutritional product labeling, processed food additive policies and consumer health education.

Exceptional contact elasticity of human enamel in nanoindentation test

ObjectiveTooth enamel has unsurpassed hardness and stiffness among mammalian tissue structures. Such stiff materials are usually brittle, yet mature enamel can survive for a lifetime. Understanding the nanoscale origin of enamel durability is important for developing advanced load-bearing biomaterials. Here, nanoscale exceptional contact elasticity of the human tooth enamel, based on nanoindentation tests, is reported. MethodsSpherical indenter tips with radii of 243 and 1041nm were used to determine stress–strain curves of enamel. Force–displacement curves were recorded using quasi-static loading strain rates of 0.031, 0.041, and 0.061s−1. The storage moduli from a superimposed signal amplitude (dynamic strain at 220Hz) embedded during primary quasi-static loading and from quasi-static elastic theory were simultaneously measured. Modulus mapping was considered to be an extremely low quasi-static loading strain rate indentation test. ResultsThe elastic limits were 7–9GPa and 5–6GPa for the small and large indenters, respectively. The elastic–plastic transition point and elastic modulus value increased with substantially increased quasi-static loading strain rate. The results suggested that the increase of the elastic limit during high-loading strain was associated with exceptional contact elasticity at the nanoscale of the enamel structure and the consequent extension of the contact area (i.e., a temporary pile-up response, dependent on the enamel nanocrystals and protein glue). SignificanceStructural modification at this scale effectively prevents the initiation of cracking from localized strain, thus reinforcing the bulk structure. These results may provide valuable insight for conceptualizing bio-inspired nanocomposites.

Risk of acute pancreatitis after sitagliptin, a dipeptidyl peptidase - 4 inhibitors

To study the therapeutic effect of early local drug therapy on pancreatic contusion and laceration.Twenty pigs were divided into 4 groups: model(PL), 1 ml of saline; medical protein glue (EC), 1 ml of medical protein glue; ulinastatin (UL), 50000U of ulinastatin; combined treatment (UE), 1 ml of medical protein glue and 50000U of ulinastatin. 30 min after model establishment, different groups received different local drug treatments. The pancreatic function, peritoneal effusion and pancreatic pathology were observed.The UE group got the best therapeutic effect. The changes of pancreatic function and the peritoneal effusion were compared with PL group as follows. 0-6h: amylase (p < 0.01), lipase (p > 0.05), effusion (p < 0.01); 6-12h: amylase (p > 0.05), lipase (p < 0.01), effusion (p < 0.01); 12-24h: amylase (p < 0.01), lipase (p < 0.01), effusion (p < 0.01).Early local drug therapy in pancreatic contusion and laceration could effectively control the development of the disease and improve the prognosis.

Unravelling the Secrets of Catechol-Cation Binding Synergy

Aqueous electrolyte solutions, including physiological fluids and seawater, limit polymer adhesion to surfaces, yet the marine mussel produces protein glues that adhere robustly under water, even in highly adverse, such as contaminated, conditions. Adhesive mussel foot proteins commonly contain adjacent catecholic 3,4-dihydroxyphenylalanine (Dopa) and cationic lysine residues. Previous work has shown that the pairing of these residues results in significantly higher adhesion energies on inorganic surfaces than either Dopa or lysine alone. Two mechanisms for synergistic binding have been proposed: either lysine evicts adsorbed cations on the substrate, enabling subsequent binding of Dopa to the substrate; or paired Dopa and lysine residues bind simultaneously to the substrate. To evaluate the validity of these two mechanisms, a series of synthetic analogs of siderophores (bacterial iron chelators) was synthesized. The intramolecular spacing between catecholic and cationic moieties was systematically varied across the series. Adhesion forces/energies of monolayers of siderophore analogs confined between symmetrical mica surfaces were measured using a Surface Forces Apparatus (SFA). Our results show no statistically significant dependence of adhesion energy on intramolecular spacing. These results support the surface cation eviction mechanism for catechol-cation synergy, and suggest that proteins incorporating Dopa and lysine residues will display elevated adhesion energies even when the groups are not directly adjacent. The knowledge that catechol-cation binding synergy operates even when the moieties are spatially separated will guide future design of biologically inspired adhesives for medical, dental, and marine applications.

Osteopromotive Coatings: Diatom‐Inspired Silica Nanostructure Coatings with Controllable Microroughness Using an Engineered Mussel Protein Glue to Accelerate Bone Growth on Titanium‐Based Implants (Adv. Mater. 46/2017)

Osteopromotive Coatings: Diatom‐Inspired Silica Nanostructure Coatings with Controllable Microroughness Using an Engineered Mussel Protein Glue to Accelerate Bone Growth on Titanium‐Based Implants (Adv. Mater. 46/2017)

Diatom-Inspired Silica Nanostructure Coatings with Controllable Microroughness Using an Engineered Mussel Protein Glue to Accelerate Bone Growth on Titanium-Based Implants.

Silica nanoparticles (SiNPs) have been utilized to construct bioactive nanostructures comprising surface topographic features and bioactivity that enhances the activity of bone cells onto titanium-based implants. However, there have been no previous attempts to create microrough surfaces based on SiNP nanostructures even though microroughness is established as a characteristic that provides beneficial effects in improving the biomechanical interlocking of titanium implants. Herein, a protein-based SiNP coating is proposed as an osteopromotive surface functionalization approach to create microroughness on titanium implant surfaces. A bioengineered recombinant mussel adhesive protein fused with a silica-precipitating R5 peptide (R5-MAP) enables direct control of the microroughness of the surface through the multilayer assembly of SiNP nanostructures under mild conditions. The assembled SiNP nanostructure significantly enhances the in vitro osteogenic cellular behaviors of preosteoblasts in a roughness-dependent manner and promotes the in vivo bone tissue formation on a titanium implant within a calvarial defect site. Thus, the R5-MAP-based SiNP nanostructure assembly could be practically applied to accelerate bone-tissue growth to improve the stability and prolong the lifetime of medical implantable devices.

Tunable denture adhesives using biomimetic principles for enhanced tissue adhesion in moist environments.

Mussel adhesive proteins have proven to be promising biomimetic adhesive candidates for soft tissues and here for the first time we have adapted marine adhesive technology into a denture fixative application. Importantly, we have incorporated a soft tissue mimic in our in vitro adhesion technique that more closely resembles the oral mucosa than previously studied substrates. The novel biomimetic-modified adhesives showed the ability to score the highest adhesive bonding out of all the formulations included in this study, across all moisture levels. This paper will be of major interest to the Acta Biomaterialia readership since the study has illustrated the potential of biomimetic principles in the design of effective prosthodontic tissue adhesives in a series of purpose-designed in vitro experiments in the context of the challenging features of the oral environment.

Natural healing-inspired collagen-targeting surgical protein glue for accelerated scarless skin regeneration

Skin scarring after deep dermal injuries is a major clinical problem due to the current therapies limited to established scars with poor understanding of healing mechanisms. From investigation of aberrations within the extracellular matrix involved in pathophysiologic scarring, it was revealed that one of the main factors responsible for impaired healing is abnormal collagen reorganization. Here, inspired by the fundamental roles of decorin, a collagen-targeting proteoglycan, in collagen remodeling, we created a scar-preventive collagen-targeting glue consisting of a newly designed collagen-binding mussel adhesive protein and a specific glycosaminoglycan. The collagen-targeting glue specifically bound to type I collagen in a dose-dependent manner and regulated the rate and the degree of fibrillogenesis. In a rat skin excisional model, the collagen-targeting glue successfully accelerated initial wound regeneration as defined by effective reepithelialization, neovascularization, and rapid collagen synthesis. Moreover, the improved dermal collagen architecture was demonstrated by uniform size of collagen fibrils, their regular packing, and a restoration of healthy tissue component. Collectively, our natural healing-inspired collagen-targeting glue may be a promising therapeutic option for improving the healing rate with high-quality and effective scar inhibition.