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https://www.readbyqxmd.com/read/28898504/reversible-dna-protein-cross-linking-at-epigenetic-dna-marks
#1
Shaofei Ji, Hongzhao Shao, Qiyuan Han, Christopher L Seiler, Natalia Tretyakova
5-Formylcytosine (5fC) is an endogenous DNA modification frequently found within regulatory elements of mammalian genes. Although 5fC is an oxidation product of 5-methylcytosine (5mC), the two epigenetic marks show distinct genome-wide distributions and protein affinities, suggesting that they perform different functions in epigenetic signaling. A unique feature of 5fC is the presence of a potentially reactive aldehyde group in its structure. Here, we show that 5fC bases in DNA readily form Schiff base conjugates with Lys side chains of nuclear proteins in vitro and in vivo...
September 12, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28876055/supramolecular-assembly-of-peptide-amphiphiles
#2
Mark P Hendricks, Kohei Sato, Liam C Palmer, Samuel I Stupp
Peptide amphiphiles (PAs) are small molecules that contain hydrophobic components covalently conjugated to peptides. In this Account, we describe recent advances involving PAs that consist of a short peptide sequence linked to an aliphatic tail. The peptide sequence can be designed to form β-sheets among the amino acids near the alkyl tail, while the residues farthest from the tail are charged to promote solubility and in some cases contain a bioactive sequence. In water, β-sheet formation and hydrophobic collapse of the aliphatic tails induce assembly of the molecules into supramolecular one-dimensional nanostructures, commonly high-aspect-ratio cylindrical or ribbonlike nanofibers...
September 6, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28837839/genetic-and-structural-elucidation-of-capsular-polysaccharides-from-streptococcus-pneumoniae-serotype-23a-and-23b-and-comparison-to-serotype-23f
#3
Neil Ravenscroft, Aneesa Omar, Jason Hlozek, Cesarina Edmonds-Smith, Rainer Follador, Fabio Serventi, Gerd Lipowsky, Michelle M Kuttel, Paola Cescutti, Amirreza Faridmoayer
Streptococcus pneumoniae is a globally important encapsulated human pathogen with approximately 100 different serotypes recognized. Serogroup 23 consists of serotype 23F, present in licensed vaccines, and emerging serotypes 23A and 23B. Here, we report the previously unknown structures of the pneumococcal capsular polysaccharides serotype 23A and 23B determined using genetic analysis, NMR spectroscopy, composition and linkage analysis and Smith degradation (of polysaccharide 23A). The structure of the serotype 23A capsular polysaccharide is: →4)-β-D-Glcp-(1→3)-[[α-L-Rhap-(1→2)]-[Gro-(2→P→3)]-β-D-Galp-(1→4)]-β-L-Rhap-(1→...
August 18, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28813684/mimicking-mechanical-response-of-natural-tissues-strain-hardening-induced-by-transient-reticulation-in-lactose-modified-chitosan-chitlac
#4
Michela Cok, Pasquale Sacco, Davide Porrelli, Andrea Travan, Massimiliano Borgogna, Eleonora Marsich, Sergio Paoletti, Ivan Donati
The effect of transient cross-links has been explored on a lactose-modified chitosan, which previously had shown interesting biological features. The presence of galactose side chains and of the polyol spacer resulted particularly appealing for the reticulation by borate ions. The interaction between chitlac and borax was investigated by means of (11)B-NMR while rheology pointed to a marked non-linear behavior depending on the amount of borax added to the system. The presence of limited amount of cross-linking ion led to dilatant behavior when the steady flow curve was measured...
August 13, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28772607/preparation-and-characterization-of-polyurethanes-with-cross-linked-siloxane-in-the-side-chain-by-sol-gel-reactions
#5
Hui Zhao, Tong-Hui Hao, Guo-Hua Hu, Dean Shi, Da Huang, Tao Jiang, Qun-Chao Zhang
A series of novel polyurethanes containing cross-linked siloxane in the side chain (SPU) were successfully synthesized through a sol-gel process. The SPU was composed of 0%-20% N-(n-butyl)-3-aminopropyltriethoxysilane (HDI-T) modified hexamethylene diisocynate homopolymer. The effects of HDI-T content on both the structure and properties of SPU were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties tests, gel content test, water contact angle measurement and water absorption test...
February 28, 2017: Materials
https://www.readbyqxmd.com/read/28733212/the-peroxyl-radical-induced-oxidation-of-escherichia-coli-ftsz-and-its-single-tryptophan-mutant-y222w-modifies-specific-side-chains-generates-protein-cross-links-and-affects-biological-function
#6
Elizabeth Escobar-Álvarez, Fabian Leinisch, Gissela Araya, Octavio Monasterio, Lasse G Lorentzen, Eduardo Silva, Michael J Davies, Camilo López-Alarcón
FtsZ (filamenting temperature-sensitive mutant Z) is a key protein in bacteria cell division. The wild-type Escherichia coli FtsZ sequence (FtsZwt) contains three tyrosine (Tyr, Y) and sixteen methionine (Met, M) residues. The Tyr at position 222 is a key residue for FtsZ polymerization. Mutation of this residue to tryptophan (Trp, W; mutant Y222W) inhibits GTPase activity resulting in an extended time in the polymerized state compared to FtsZwt. Protein oxidation has been highlighted as a determinant process for bacteria resistance and consequently oxidation of FtsZwt and the Y222W mutant, by peroxyl radicals (ROO•) generated from AAPH (2,2'-azobis(2-methylpropionamidine) dihydrochloride) was studied...
July 18, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28717933/a-novel-ms-cleavable-azo-cross-linker-for-peptide-structure-analysis-by-free-radical-initiated-peptide-sequencing-frips
#7
Claudio Iacobucci, Christoph Hage, Mathias Schäfer, Andrea Sinz
The chemical cross-linking/mass spectrometry (MS) approach is a growing research field in structural proteomics that allows gaining insights into protein conformations. It relies on creating distance constraints between cross-linked amino acid side chains that can further be used to derive protein structures. Currently, the most urgent task for designing novel cross-linking principles is an unambiguous and automated assignment of the created cross-linked products. Here, we introduce the homobifunctional, amine-reactive, and water soluble cross-linker azobisimidoester (ABI) as a prototype of a novel class of cross-linkers...
July 17, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28690007/bioreactor-induced-mesenchymal-progenitor-cell-differentiation-and-elastic-fiber-assembly-in-engineered-vascular-tissues
#8
Shigang Lin, Kibret Mequanint
In vitro maturation of engineered vascular tissues (EVT) requires the appropriate incorporation of smooth muscle cells (SMC) and extracellular matrix (ECM) components similar to native arteries. To this end, the aim of the current study was to fabricate 4mm inner diameter vascular tissues using mesenchymal progenitor cells seeded into tubular scaffolds. A dual-pump bioreactor operating either in perfusion or pulsatile perfusion mode was used to generate physiological-like stimuli to promote progenitor cell differentiation, extracellular elastin production, and tissue maturation...
September 1, 2017: Acta Biomaterialia
https://www.readbyqxmd.com/read/28654756/hydrogels-with-a-memory-dual-responsive-organometallic-poly-ionic-liquid-s-with-hysteretic-volume-phase-transition
#9
Kaihuan Zhang, Xueling Feng, Chongnan Ye, Mark A Hempenius, G Julius Vancso
We report on the synthesis and structure-property relations of a novel, dual-responsive organometallic poly(ionic liquid) (PIL), consisting of a poly(ferrocenylsilane) backbone of alternating redox-active, silane-bridged ferrocene units and tetraalkylphosphonium sulfonate moieties in the side groups. This PIL is redox responsive due to the presence of ferrocene in the backbone and also exhibits a lower critical solution temperature (LCST)-type thermal responsive behavior. The LCST phase transition originates from the interaction between water molecules and the ionic substituents and shows a concentration-dependent, tunable transition temperature in aqueous solution...
July 26, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28636365/sustainable-elastomers-from-renewable-biomass
#10
Zhongkai Wang, Liang Yuan, Chuanbing Tang
Sustainable elastomers have undergone explosive growth in recent years, partly due to the resurgence of biobased materials prepared from renewable natural resources. However, mounting challenges still prevail: How can the chemical compositions and macromolecular architectures of sustainable polymers be controlled and broadened? How can their processability and recyclability be enabled? How can they compete with petroleum-based counterparts in both cost and performance? Molecular-biomass-derived polymers, such as polymyrcene, polymenthide, and poly(ε-decalactone), have been employed for constructing thermoplastic elastomers (TPEs)...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28570824/protein-epitope-mimetics-from-new-antibiotics-to-supramolecular-synthetic-vaccines
#11
Katja Zerbe, Kerstin Moehle, John A Robinson
Protein epitope mimetics provide powerful tools to study biomolecular recognition in many areas of chemical biology. They may also provide access to new biologically active molecules and potentially to new classes of drug and vaccine candidates. Here we highlight approaches for the design of folded, structurally defined epitope mimetics, by incorporating backbone and side chains of hot residues onto a stable constrained scaffold. Using robust synthetic methods, the structural, biological, and physical properties of epitope mimetics can be optimized, by variation of both side chain and backbone chemistry...
June 1, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28526748/the-sialate-o-acetylesterase-esta-from-gut-bacteroidetes-species-enables-sialidase-mediated-cross-species-foraging-of-9-o-acetylated-sialoglycans
#12
Lloyd S Robinson, Warren G Lewis, Amanda L Lewis
The gut harbors many symbiotic, commensal, and pathogenic microbes that break down and metabolize host carbohydrates. Sialic acids are prominent outermost carbohydrates on host glycoproteins called mucins and protect underlying glycan chains from enzymatic degradation. Sialidases produced by some members of the colonic microbiota can promote the expansion of several potential pathogens (e.g. Clostridium difficile, Salmonella, and Escherichia coli) that do not produce sialidases. O-Acetyl ester modifications of sialic acids help resist the action of many sialidases and are present at high levels in the mammalian colon...
July 14, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28507244/inhibition-of-staphylococcus-aureus-cell-wall-biosynthesis-by-desleucyl-oritavancin-a-quantitative-peptidoglycan-composition-analysis-by-mass-spectrometry
#13
James D Chang, Erin E Foster, Aanchal N Thadani, Alejandro J Ramirez, Sung Joon Kim
Oritavancin is a lipoglycopeptide antibiotic that exhibits potent activities against vancomycin-resistant Gram-positive pathogens. Oritavancin differs from vancomycin by a hydrophobic side chain attached to the drug disaccharide, which forms a secondary binding site to enable oritavancin binding to the cross-linked peptidoglycan in the cell wall. The mode of action of secondary binding site was investigated by measuring the changes in the peptidoglycan composition of Staphylococcus aureus grown in the presence of desleucyl-oritavancin at subinhibitory concentration using liquid chromatography-mass spectrometry (LC-MS)...
August 1, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28506526/molecular-simulation-and-biochemical-studies-support-an-elevator-type-transport-mechanism-in%C3%A2-eiic
#14
LETTER
Jumin Lee, Zhenning Ren, Ming Zhou, Wonpil Im
Enzyme IIC (EIIC) is a membrane-embedded sugar transport protein that is part of the phosphoenolpyruvate-dependent phosphotransferases. Crystal structures of two members of the glucose EIIC superfamily, bcChbC in the inward-facing conformation and bcMalT in the outward-facing conformation, were previously solved. Comparing the two structures led us to the hypothesis that sugar translocation could be achieved by an elevator-type transport mechanism in which a transport domain binds to the substrate and, through rigid body motions, transports it across the membrane...
June 6, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28448030/synthesis-of-biocompatible-liquid-crystal-elastomer-foams-as-cell-scaffolds-for-3d-spatial-cell-cultures
#15
Marianne E Prévôt, Senay Ustunel, Leah E Bergquist, Richard Cukelj, Yunxiang Gao, Taizo Mori, Lindsay Pauline, Robert J Clements, Elda Hegmann
Here, we present a step-by-step preparation of a 3D, biodegradable, foam-like cell scaffold. These scaffolds were prepared by cross-linking star block co-polymers featuring cholesterol units as side-chain pendant groups, resulting in smectic-A (SmA) liquid crystal elastomers (LCEs). Foam-like scaffolds, prepared using metal templates, feature interconnected microchannels, making them suitable as 3D cell culture scaffolds. The combined properties of the regular structure of the metal foam and of the elastomer result in a 3D cell scaffold that promotes not only higher cell proliferation compared to conventional porous templated films, but also better management of mass transport (i...
April 11, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28423990/self-assembled-nanogel-of-cholesterol-bearing-xyloglucan-as-a-drug-delivery-nanocarrier
#16
Shin-Ichi Sawada, Hiroko Yukawa, Shigeo Takeda, Yoshihiro Sasaki, Kazunari Akiyoshi
Xyloglucan (XG) is a multibranched polysaccharide consisting of a main chain β-1,4-glucan with xylose and galactose side chains. In this study, cholesterol-bearing XG (CHXG) was synthesized by the reaction of XG with cholesteryl N-(6-isocyanatohexyl) carbamate. The CHXG molecules self-assembled in water to form nanogels consisting of about 100 molecules of XG, and were characterized using light scattering and transmission electron microscopy. The number of cholesteryl groups per physical cross-linking site was estimated using a fluorescence quenching method...
July 2017: Journal of Biomaterials Science. Polymer Edition
https://www.readbyqxmd.com/read/28409923/the-catalase-activity-of-catalase-peroxidases-is-modulated-by-changes-in-the-pka-of-the-distal-histidine
#17
Miguel Machuqueiro, Bruno Victor, Jacek Switala, Jacylyn Villanueva, Carme Rovira, Ignacio Fita, Peter C Loewen
The unusual Met-Tyr-Trp adduct composed of cross-linked side chains along with an associated mobile Arg is essential for catalase activity in catalase-peroxidases. In addition, acidic residues in the entrance channel, in particular an Asp and a Glu ∼7 and ∼15 Å, respectively, from the heme, significantly enhance catalase activity. The mechanism by which these channel carboxylates influence catalase activity is the focus of this work. Seventeen new variants with fewer and additional acidic residues have been constructed and characterized structurally and for enzymatic activity, revealing that their effect on activity is roughly inversely proportional to their distance from the heme and adduct, suggesting that the electrostatic potential of the heme cavity may be affected...
May 2, 2017: Biochemistry
https://www.readbyqxmd.com/read/28381672/supramolecular-polymeric-materials-containing-cyclodextrins
#18
REVIEW
Masaki Nakahata, Yoshinori Takashima, Akira Harada
Smart design of polymeric materials may lead to intelligent materials exhibiting unique functional properties. Looking at nature, living systems use specific and reversible intermolecular interactions in realizing complex functions. Hence reversible bonds based on selective molecular recognition can impart artificial materials with unique functional properties. This review mainly focuses on supramolecular polymeric materials based on cyclodextrin-based host-guest interactions. Polymeric materials using molecular recognition at polymer main chain, side chain, and termini are described...
2017: Chemical & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28301130/graphene-embedded-hydrogel-nanofibers-for-detection-and-removal-of-aqueous-phase-dyes
#19
Kyungun Im, Duong Nguyen Nguyen, Saerona Kim, Hye Jeong Kong, Yukyung Kim, Chul Soon Park, Oh Seok Kwon, Hyeonseok Yoon
A facile route to graphene/polymer hydrogel nanofibers was developed. An aqueous dispersion of graphene (containing >40% bilayer graphene flakes) stabilized by a functionalized water-soluble polymer with phenyl side chains was successfully electrospun to yield nanofibers. Subsequent vapor-phase cross-linking of the nanofibers produced graphene-embedded hydrogel nanofibers (GHNFs). Interestingly, the GHNFs showed chemical sensitivity to the cationic dyes methylene blue (MB) and crystal violet (CV) in the aqueous phase...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28299927/supramolecular-hydrogels-based-on-dna-self-assembly
#20
Yu Shao, Haoyang Jia, Tianyang Cao, Dongsheng Liu
Extracellular matrix (ECM) provides essential supports three dimensionally to the cells in living organs, including mechanical support and signal, nutrition, oxygen, and waste transportation. Thus, using hydrogels to mimic its function has attracted much attention in recent years, especially in tissue engineering, cell biology, and drug screening. However, a hydrogel system that can merit all parameters of the natural ECM is still a challenge. In the past decade, deoxyribonucleic acid (DNA) has arisen as an outstanding building material for the hydrogels, as it has unique properties compared to most synthetic or natural polymers, such as sequence designability, precise recognition, structural rigidity, and minimal toxicity...
March 16, 2017: Accounts of Chemical Research
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