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https://www.readbyqxmd.com/read/28534525/covalently-linked-dengue-virus-envelope-glycoprotein-dimers-reduce-exposure-of-the-immunodominant-fusion-loop-epitope
#1
Alexander Rouvinski, Wanwisa Dejnirattisai, Pablo Guardado-Calvo, Marie-Christine Vaney, Arvind Sharma, Stéphane Duquerroy, Piyada Supasa, Wiyada Wongwiwat, Ahmed Haouz, Giovanna Barba-Spaeth, Juthathip Mongkolsapaya, Félix A Rey, Gavin R Screaton
A problem in the search for an efficient vaccine against dengue virus is the immunodominance of the fusion loop epitope (FLE), a segment of the envelope protein E that is buried at the interface of the E dimers coating mature viral particles. Anti-FLE antibodies are broadly cross-reactive but poorly neutralizing, displaying a strong infection enhancing potential. FLE exposure takes place via dynamic 'breathing' of E dimers at the virion surface. In contrast, antibodies targeting the E dimer epitope (EDE), readily exposed at the E dimer interface over the region of the conserved fusion loop, are very potent and broadly neutralizing...
May 23, 2017: Nature Communications
https://www.readbyqxmd.com/read/28533376/b12-dependent-photoresponsive-protein-hydrogels-for-controlled-stem-cell-protein-release
#2
Ri Wang, Zhongguang Yang, Jiren Luo, I-Ming Hsing, Fei Sun
Thanks to the precise control over their structural and functional properties, genetically engineered protein-based hydrogels have emerged as a promising candidate for biomedical applications. Given the growing demand for creating stimuli-responsive "smart" hydrogels, here we show the synthesis of entirely protein-based photoresponsive hydrogels by covalently polymerizing the adenosylcobalamin (AdoB12)-dependent photoreceptor C-terminal adenosylcobalamin binding domain (CarHC) proteins using genetically encoded SpyTag-SpyCatcher chemistry under mild physiological conditions...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28533368/bio-inspired-self-healing-structural-color-hydrogel
#3
Fanfan Fu, Zhuoyue Chen, Ze Zhao, Huan Wang, Luoran Shang, Zhongze Gu, Yuanjin Zhao
Biologically inspired self-healing structural color hydrogels were developed by adding a glucose oxidase (GOX)- and catalase (CAT)-filled glutaraldehyde cross-linked BSA hydrogel into methacrylated gelatin (GelMA) inverse opal scaffolds. The composite hydrogel materials with the polymerized GelMA scaffold could maintain the stability of an inverse opal structure and its resultant structural colors, whereas the protein hydrogel filler could impart self-healing capability through the reversible covalent attachment of glutaraldehyde to lysine residues of BSA and enzyme additives...
May 22, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28532097/influence-of-telopeptides-on-the-structural-and-physical-properties-of-polymeric-and-monomeric-acid-soluble-type-i-collagen
#4
Róisín Holmes, Steve Kirk, Giuseppe Tronci, Xuebin Yang, David Wood
Currently two factors hinder the use of collagen as building block of regenerative devices: the limited mechanical strength in aqueous environment, and potential antigenicity. Polymeric collagen is naturally found in the cross-linked state and is mechanically tougher than the monomeric, acid-soluble collagen ex vivo. The antigenicity of collagen, on the other hand, is mainly ascribed to inter-species variations in amino acid sequences of the non-helical terminal telopeptides. These telopeptides can be removed through enzymatic treatment to produce atelocollagen, although the effect of this cleavage on triple helix organization, amino acidic composition and thermal properties is often disregarded...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28532053/functionalized-fe3o4-graphene-oxide-nanocomposites-with-hairpin-aptamers-for-the-separation-and-preconcentration-of-trace-pb-2-from-biological-samples-prior-to-determination-by-icp-ms
#5
Mojtaba Shamsipur, Leila Farzin, Mahmoud Amouzadeh Tabrizi, Shahab Sheibani
Lead (Pb) as a topically poisonous metal represents a serious threat to the ecological environment and especially to human beings. Therefore, it is urgent to develop a rapid and reliable monitoring technique for this heavy metal in the environmental samples. In the present study, we have designed a selective and sensitive method for the determination of ultratrace contents of Pb(2+) in biological samples, based on the guanine (G)-quadruplex formed by the aptamer with hairpin structure and Pb(2+). For this purpose, Pb(2+) specific aptamer serving as affinity probe to capture and separate trace amounts of the analyte, was covalently linked to Fe3O4/graphene oxide (GO) surface by using a suitable cross-linking agent...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28531973/properties-and-toughening-mechanisms-of-pva-pam-double-network-hydrogels-prepared-by-freeze-thawing-and-anneal-swelling
#6
Kangkang Ou, Xia Dong, Chengling Qin, Xinan Ji, Jinxin He
It is well known that preparation method of hydrogels has a significant effect on their properties. In this paper, freeze-thawing and anneal-swelling were applied to prepare poly(vinyl alcohol)/polyacrylamide (PVA/PAM) double-network hydrogels with covalently and physically cross-linked networks. The properties of these hydrogels were investigated and compared to control hydrogels. Results indicated that hydrogels fabricated by freeze-thawing show larger pores size and higher swelling capacity than those made by anneal-swelling and control hydrogels...
August 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28525280/self-healing-self-assembled-%C3%AE-sheet-peptide-poly-%C3%AE-glutamic-acid-hybrid-hydrogels
#7
David E Clarke, E Thomas Pashuck, Sergio Bertazzo, Jonathan V M Weaver, Molly M Stevens
Self-assembled biomaterials are an important class of materials that can be injected and formed in situ. However, they often are not able to meet the mechanical properties necessary for many biological applications, losing mechanical properties at low strains. We synthesized hybrid hydrogels consisting of a poly(γ-glutamic acid) polymer network physically cross-linked via grafted self-assembling β-sheet peptides to provide non-covalent cross-linking through β-sheet assembly, reinforced with a polymer backbone to improve strain stability...
May 19, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28521974/research-progress-in-coating-techniques-of-alginate-gel-polymer-for-cell-encapsulation
#8
REVIEW
Guillermo Simó, Encarnación Fernández-Fernández, Josefina Vila-Crespo, Violeta Ruipérez, José Manuel Rodríguez-Nogales
Cell encapsulation is used as a biotechnology tool to solve the technological problems derived from handling and application of cells in a great range of fields. This involves immobilization of the cells within a polymeric gel that permits the preservation of their metabolic activity. Alginate is widely established as the most suitable polymer for cell encapsulation. However, alginate gel capsules suffer several disadvantages because of their lack of mechanical and chemical stability. This review summarizes results of recent advances in coating techniques that include ionic and covalent cross-linking between alginate and coating materials for cell encapsulation as a strategy to solve the disadvantages mentioned before...
August 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28521498/phenol-induced-o-o-bond-cleavage-in-a-low-spin-heme-peroxo-copper-complex-implications-for-o2-reduction-in-heme-copper-oxidases
#9
Andrew W Schaefer, Matthew T Kieber-Emmons, Suzanne M Adam, Kenneth D Karlin, Edward I Solomon
This study evaluates the reaction of a biomimetic heme-peroxo-copper complex {[(DCHIm)(F8)FeIII]-(O22-)-[CuII(AN)]}+ (1) with a phenolic substrate, involving a net H-atom abstraction to cleave the bridging peroxo O-O bond that produces FeIV=O, CuII-OH and phenoxyl radical moieties, analogous to the chemistry carried out in heme-copper oxidases (HCOs). A 3D potential energy surface generated for this reaction reveals two possible reaction pathways: one involves nearly complete proton transfer from the phenol to the peroxo ligand before the barrier; the other involves O-O homolysis where the phenol remains H-bonding to the peroxo O(Cu) in the transition state, and transfers the proton after the barrier...
May 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28520409/feco-anchored-reduced-graphene-oxide-framework-based-soft-composites-containing-carbon-nanotubes-as-highly-efficient-microwave-absorbers-with-excellent-heat-dissipation-ability
#10
Injamamul Arief, Sourav Biswas, Suryasarathi Bose
Conducting polymer composites containing ferromagnetic grafted-graphene derivatives are already appreciated for their lightweight, flexibility and cost effectiveness in terms of microwave absorption. To further leverage the said properties of this wonder material, we propose a highly efficient replacement by blending conducting multi-wall carbon nanotube (MWCNT) and FeCo anchored covalent cross-linked reduced graphene oxide (rGO) with polyvinylidene fluoride (PVDF). Interconnected conducting network of MWCNTs introduces higher electrical conductivity in the blend which is essential for microwave absorption...
May 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28518087/multimer-page-a-method-for-capturing-and-resolving-protein-complexes-in-biological-samples
#11
Tyler Rhinesmith, Bryan A Killinger, Akhil Sharma, Anna Moszczynska
There are many well-developed methods for purifying and studying single proteins and peptides. However, most cellular functions are carried out by networks of interacting protein complexes, which are often difficult to investigate because their binding is non-covalent and easily perturbed by purification techniques. This work describes a method of stabilizing and separating native protein complexes from unmodified tissue using two-dimensional polyacrylamide gel electrophoresis. Tissue lysate is loaded onto a non-denaturing blue-native polyacrylamide gel, then an electric current is applied until the protein migrates a short distance into the gel...
May 5, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28499201/folate-functionalized-assembly-of-low-density-lipoprotein-sodium-carboxymethyl-cellulose-nanoparticles-for-targeted-delivery
#12
Hongshan Liang, Lei He, Bin Zhou, Bin Li, Jing Li
In this study, well-defined folate (FA)-functionalized low density lipoproteins (LDL)/sodium carboxymethyl cellulose (CMC) nanoparticles (NP) were first formulated, utilized in tumor targeting and pH-triggered drug release. CMC was modified with FA before the preparation of NP. A model anti-tumor drug, doxorubicin (DOX), was effectively loaded into the LDL/CMC-FA NP by ionic bonding and hydrophobic interactions. To enhance non-covalent encapsulation stability, self-assembly of DOX-loaded LDL/CMC-FA NP (NP-DOX) was cross-linked by multivalent cations such as Ca(2+) (Ca(2+)-NP-DOX)...
May 2, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28496323/a-novel-nanoemulsion-based-method-to-produce-ultrasmall-water-dispersible-nanoparticles-from-chitosan-surface-modified-with-cell-penetrating-peptide-for-oral-delivery-of-proteins-and-peptides
#13
Ghullam Reza Barbari, Farid Abedin Dorkoosh, Mohsen Amini, Mohammad Sharifzadeh, Fateme Atyabi, Saeed Balalaie, Niyousha Rafiee Tehrani, Morteza Rafiee Tehrani
A simple and reproducible water-in-oil (W/O) nanoemulsion technique for making ultrasmall (<15 nm), monodispersed and water-dispersible nanoparticles (NPs) from chitosan (CS) is reported. The nano-sized (50 nm) water pools of the W/O nanoemulsion serve as "nano-containers and nano-reactors". The entrapped polymer chains of CS inside these "nano-reactors" are covalently cross-linked with the chains of polyethylene glycol (PEG), leading to rigidification and formation of NPs. These NPs possess excessive swelling properties in aqueous medium and preserve integrity in all pH ranges due to chemical cross-linking with PEG...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28482567/polymerizable-aggregation-induced-emission-dye-for-preparation-of-cross-linkable-fluorescent-nanoprobes-with-ultra-low-critical-micelle-concentrations
#14
Long Huang, Meiying Liu, Liucheng Mao, Xiqi Zhang, Dazhuang Xu, Qing Wan, Qiang Huang, Yingge Shi, Fengjie Deng, Xiaoyong Zhang, Yen Wei
In recent years, aggregation-induced emission (AIE) dyes based fluorescent organic nanoparticles (FONs) have achieved significant progress in various biomedical applications. In this work, we developed a covalent strategy to prepare biocompatible AIE-active dyes based cross-linked copolymers (MPC-POSS-PhE) via controllable reversible addition fragmentation chain transfer (RAFT) polymerization using zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC), polymerizable AIE dye (named as PhE) and 8-vinyl polyoctahedral silsesquioxanes (POSS) as monomers...
July 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28481303/interaction-of-biliverdin-chromophore-with-near-infrared-fluorescent-protein-bphp1-fp-engineered-from-bacterial-phytochrome
#15
Olesya V Stepanenko, Olga V Stepanenko, Irina M Kuznetsova, Daria M Shcherbakova, Vladislav V Verkhusha, Konstantin K Turoverov
Near-infrared (NIR) fluorescent proteins (FPs) designed from PAS (Per-ARNT-Sim repeats) and GAF (cGMP phosphodiesterase/adenylate cyclase/FhlA transcriptional activator) domains of bacterial phytochromes covalently bind biliverdin (BV) chromophore via one or two Cys residues. We studied BV interaction with a series of NIR FP variants derived from the recently reported BphP1-FP protein. The latter was engineered from a bacterial phytochrome RpBphP1, and has two reactive Cys residues (Cys15 in the PAS domain and Cys256 in the GAF domain), whereas its mutants contain single Cys residues either in the PAS domain or in the GAF domain, or no Cys residues...
May 8, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28476891/drosophila-tg-a-transglutaminase-is-secreted-via-an-unconventional-golgi-independent-mechanism-involving-exosomes-and-two-types-of-fatty-acylations
#16
Toshio Shibata, Jinki Hadano, Daichi Kawasaki, Xiaoqing Dong, Shun-Ichiro Kawabata
Transglutaminases (TGs) play essential intracellular and extracellular roles by covalently cross-linking many proteins. Drosophila TG is encoded by one gene and has two alternative splicing-derived isoforms, TG-A and TG-B, which contain distinct N-terminal 46- and 38-amino acid sequences, respectively. The TGs identified to date do not have a typical endoplasmic reticulum (ER)-signal peptide, and the molecular mechanisms of their secretion under physiologic conditions are unclear. Immunocytochemistry revealed that TG-A localizes to multivesicular-like structures, whereas TG-B localizes to the cytosol...
May 5, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28470667/autoreactive-monoclonal-antibodies-from-patients-with-primary-biliary-cholangitis-recognize-environmental-xenobiotics
#17
Toshihiro Tanaka, Weici Zhang, Ying Sun, Zongwen Shuai, Asiya Chida, Thomas P Kenny, Guo-Xiang Yang, Ignacio Sanz, Aftab Ansai, Christopher L Bowlus, Gregory C Ippolito, Ross L Coppel, Kazuichi Okazaki, Xiao-Song He, Patrick S C Leung, M Eric Gershwin
A major problem in autoimmunity has been identification of the earliest events that lead to breach of tolerance. Although there have been major advances in dissecting effector pathways and the multi-lineage immune responses to mitochondrial self-antigens in primary biliary cholangitis (PBC), the critical links between environmental factors and tolerance remain elusive. We hypothesized that environmental xenobiotic modification of the E2 subunit of the pyruvate dehydrogenase (PDC-E2) inner lipoyl domain can lead to loss of tolerance to genetically susceptible hosts...
May 3, 2017: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
https://www.readbyqxmd.com/read/28464409/tyrosine-or-tryptophan-modifying-a-metalloradical-catalytic-site-by-removal-of-the-cys-tyr-cross-link-in-the-galactose-6-oxidase-homologue-glxa
#18
Amanda K Chaplin, Caterina Bernini, Adalgisa Sinicropi, Riccardo Basosi, Jonathan A R Worrall, Dimitri A Svistunenko
The concerted redox action of a metal ion and an organic cofactor is a unique way to maximize the catalytic power of an enzyme. An example of such synergy is the fungal galactose 6-oxidase, which has inspired the creation of biomimetic copper oxidation catalysts. Galactose 6-oxidase and its bacterial homologue, GlxA, possess a metalloradical catalytic site that contains a free radical on a covalently linked Cys-Tyr and a copper atom. Such a catalytic site enables for the two-electron oxidation of alcohols to aldehydes...
May 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28443615/the-plant-cell-wall-enzyme-atxth3-catalyses-covalent-cross-linking-between-cellulose-and-cello-oligosaccharide
#19
Naoki Shinohara, Naoki Sunagawa, Satoru Tamura, Ryusuke Yokoyama, Minoru Ueda, Kiyohiko Igarashi, Kazuhiko Nishitani
Cellulose is an economically important material, but routes of its industrial processing have not been fully explored. The plant cell wall - the major source of cellulose - harbours enzymes of the xyloglucan endotransglucosylase/hydrolase (XTH) family. This class of enzymes is unique in that it is capable of elongating polysaccharide chains without the requirement for activated nucleotide sugars (e.g., UDP-glucose) and in seamlessly splitting and reconnecting chains of xyloglucan, a naturally occurring soluble analogue of cellulose...
April 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28440640/nucleic-acid-nanocapsules-for-enzyme-triggered-drug-release
#20
Joseph K Awino, Saketh Gudipati, Alyssa K Hartmann, Joshua J Santiana, Dominic F Cairns-Gibson, Nicole Gomez, Jessica L Rouge
Herein we describe a nucleic acid functionalized nanocapsule in which nucleic acid ligands are assembled and disassembled in the presence of enzymes. The particles are fully degradable in response to esterases due to an embedded ester cross-linker in the particle's core. During synthesis the nanocapsules can be loaded with hydrophobic small molecules and post self-assembly undergo covalent cross-linking using copper catalyzed click chemistry. They can then be functionalized with thiolated DNA through stepwise thiolyne chemistry using UV light irradiation...
April 25, 2017: Journal of the American Chemical Society
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