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https://www.readbyqxmd.com/read/28099013/dynamic-nuclear-polarization-signal-enhancement-with-high-affinity-biradical-tags
#1
Rivkah Tamar Rogawski, Ivan V Sergeyev, Yongjun Li, Maria Francesca Ottaviani, Virginia W Cornish, Ann E McDermott
Dynamic nuclear polarization is an emerging technique for sensitizing solid state NMR experiments by transferring polarization from electrons to nuclei. Stable biradicals, the polarization source for the cross effect mechanism, are typically co-dissolved at millimolar concentrations with proteins of interest. Here we describe the high-affinity biradical tag TMP-T, created by covalently linking trimethoprim, a nanomolar affinity ligand of dihydrofolate reductase (DHFR), to the biradical polarizing agent TOTAPOL...
January 18, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28092128/biomimetic-supramolecular-polymer-networks-exhibiting-both-toughness-and-self-recovery
#2
Ji Liu, Cindy Soo Yun Tan, Ziyi Yu, Yang Lan, Chris Abell, Oren A Scherman
Biomimetic supramolecular dual networks: By mimicking the structure/function model of titin, integration of dynamic cucurbit[8]uril mediated host-guest interactions with a trace amount of covalent cross-linking leads to hierarchical dual networks with intriguing toughness, strength, elasticity, and energy dissipation properties. Dynamic host-guest interactions can be dissociated as sacrificial bonds and their facile reformation results in self-recovery of the dual network structure as well as its mechanical properties...
January 16, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28087273/chitosan-cross-linked-with-poly-ethylene-glycol-dialdehyde-via-reductive-amination-as-effective-controlled-release-carriers-for-oral-protein-drug-delivery
#3
Zi-Wei Jing, Zhi-Wei Ma, Chen Li, Yi-Yang Jia, Min Luo, Xi-Xi Ma, Si-Yuan Zhou, Bang-Le Zhang
The covalently cross-linked chitosan-poly(ethylene glycol)1540 derivatives have been developed as a controlled release system with potential for the delivery of protein drug. The swelling characteristics of the hydrogels based on these derivatives as the function of different PEG content and the release profiles of a model protein (bovine serum albumin, BSA) from the hydrogels were evaluated in simulated gastric fluid with or without enzyme in order to simulate the gastrointestinal tract conditions. The derivatives cross-linked with difunctional PEG1540-dialdehyde via reductive amination can swell in alkaline pH and remain insoluble in acidic medium...
December 31, 2016: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28079984/medical-application-of-glycosaminoglycans-a-review
#4
REVIEW
Alexander Köwitsch, Guoying Zhou, Thomas Groth
The characteristic molecular composition of the different glycosaminoglycans (GAG) is related to their role as structural components and regulators of a multitude of functions of proteins, cells and tissues in the human body. Therefore, it is not surprising that GAG are widely used as coating materials for implants, components of 3D-constructs like tissue engineering scaffolds and hydrogels, but also as diagnostic devices like biosensors and in controlled release applications. Beside a physisorption or encapsulation of GAG, these applications often require their chemical modification to allow a stable covalent attachment on surfaces or cross-linking reactions with other molecules...
January 12, 2017: Journal of Tissue Engineering and Regenerative Medicine
https://www.readbyqxmd.com/read/28075068/binding-and-processing-of-%C3%AE-lactam-antibiotics-by-the-transpeptidase-ldtmt2-from-mycobacterium-tuberculosis
#5
Eva Maria Steiner, Gunter Schneider, Robert Schnell
β-lactam antibiotics represent a novel direction in the chemotherapy of tuberculosis that brings the peptidoglycan layer of the complex mycobacterial cell wall in focus as therapeutic target. Peptidoglycan stability in Mycobacterium tuberculosis especially during infection relies on the non-conventional peptide cross-links formed by L,D-transpeptidases. These enzymes are known to be inhibited by β-lactams, primarily carbapenems, leading to a stable covalent modification at the enzyme active site. A panel of sixteen β-lactams antibiotics was characterized by inhibition kinetics, mass spectrometry and x-ray crystallography to identify efficient compounds and study their action on the essential transpeptidase LdtMt2 ...
January 11, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28068470/virtual-cross-linking-of-the-active-nemorubicin-metabolite-pnu-159682-to-double-stranded-dna
#6
Matteo Scalabrin, Luigi Quintieri, Manlio Palumbo, Federico Riccardi Sirtori, Barbara Gatto
The DNA alkylating mechanism of PNU-159682 (PNU), a highly potent metabolite of the anthracycline nemorubicin, was investigated by gel-electrophoretic, HPLC-UV and micro-HPLC/mass spectrometry (MS) measurements. PNU quickly reacted with double-stranded oligonucleotides, but not with single-stranded sequences, to form covalent adducts which were detectable by denaturing polyacrylamide gel electrophoresis (DPAGE). Ion-pair reverse-phase HPLC-UV analysis on CG rich duplex sequences having a 5'-CCCGGG-3' central core showed the formation of two types of adducts with PNU, which were stable and could be characterized by micro-HPLC/MS...
January 9, 2017: Chemical Research in Toxicology
https://www.readbyqxmd.com/read/28055113/assessment-of-telomere-length-phenotype-and-dna-content
#7
Theodoros Kelesidis, Ingrid Schmid
Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior cell separation. After cells are stained for surface immunofluorescence, antigen-antibody complexes are covalently cross-linked onto cell membranes before FISH with a telomere-specific probe...
January 5, 2017: Current Protocols in Cytometry
https://www.readbyqxmd.com/read/28045517/spray-drying-for-making-covalent-chemistry-postsynthetic-modification-of-metal-organic-frameworks
#8
Luis Garzón-Tovar, Sabina Rodríguez-Hermida, Inhar Imaz, Daniel Maspoch
Covalent postsynthetic modification (PSM) of metal-organic frameworks (MOFs) has attracted much attention due to the possibility of tailoring the properties of these porous materials. Schiff-base condensation between an amine and an aldehyde is one of the most common reactions in the PSM of MOFs. Here, we report the use of the spray drying technique to perform this class of organic reactions, either between discrete organic molecules or on the pore surfaces of MOFs, in a very fast (1-2 s) and continuous way...
January 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28038741/tunable-softening-and-toughening-of-individualized-cellulose-nanofibers-polyurethane-urea-elastomer-composites
#9
Minwoo Lee, Min Haeng Heo, Hwi-Hui Lee, Young-Wun Kim, Jihoon Shin
A series of elastomeric nanocomposites with superior tensile strength and extensibility, simultaneously exhibiting softening, was prepared using in situ polymerization by homogeneously dispersing TEMPO-oxidized cellulose individualized nanofibers (TOCNs) in a polyurethane urea (PUU) matrix. The structure of these PUU composites covalently cross-linked with the TOCNs was characterized. It was interesting to find that the amount and size of the hard domains in the composites gradually decreased by introducing crosslinkable TOCNs...
March 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28032943/mass-spectrometry-based-tools-to-characterize-dna-protein-cross-linking-by-bis-electrophiles
#10
Arnold Groehler, Amanda Degner, Natalia Y Tretyakova
DNA-protein cross-links (DPCs) are unusually bulky DNA adducts that form in cells as a result of exposure to endogenous and exogenous agents including reactive oxygen species, ultraviolet light, ionizing radiation, environmental agents (e.g. transition metals, formaldehyde, 1,2-dibromoethane, 1,3-butadiene) and common chemotherapeutic agents. Covalent DPCs are cytotoxic and mutagenic due to their ability to interfere with faithful DNA replication and prevent accurate gene expression. Key to our understanding of the biological significance of DPC formation is identifying the proteins most susceptible to forming these unusually bulky and complex lesions and quantifying the extent of DNA-protein cross-linking in cells and tissues...
December 29, 2016: Basic & Clinical Pharmacology & Toxicology
https://www.readbyqxmd.com/read/28029038/dual-electrochemiluminescence-signal-system-for-in-situ-and-simultaneous-evaluation-of-multiple-cell-surface-receptors
#11
Bin Zhou, Youyi Qiu, Qingqing Wen, Mingyao Zhu, Peihui Yang
A mutiplex cytosensor based on a dual electrochemiluminescence (ECL) signal system was fabricated for in situ and simultaneous detection of the expression levels of multiple cell-surface receptors, mannose and epidermal growth factor receptor (EGFR), using luminol-capped gold nanoparticles (Au@luminol) and CdS quantum dots (CdS QDs) as potential-resolved ECL nanoprobes. Two spatially resolved areas on indium tin oxide (ITO) electrodes were modified with polyaniline (PANI) by electropolymerization, on which gold nanoparticles (AuNPs) were attached to strengthen conductivity and stability of the sensing interface...
January 11, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28026147/development-of-a-novel-immobilization-method-by-using-microgels-to-keep-enzyme-in-hydrated-microenvironment-in-porous-hydrophobic-membranes
#12
Giuseppe Vitola, Dominic Büning, Jens Schumacher, Rosalinda Mazzei, Lidietta Giorno, Mathias Ulbricht
Using colloidal polyacrylamide (PAAm) microgels as carriers, a novel strategy for covalent immobilization of enzymes maintained in hydrated microenvironment on/in a macroporous surface-functionalized hydrophobic polyvinylidene fluoride (PVDF) membrane is developed. The PAAm microgels are synthesized by inverse miniemulsion polymerization, and first the parameters are investigated which are suited to obtain particles in the desired size range, 100-200 nm, with narrow size distribution. Amino functions are then imparted to the microgels applying the Hofmann reaction...
December 27, 2016: Macromolecular Bioscience
https://www.readbyqxmd.com/read/28024547/metrics-of-rhamnogalacturonan-i-with-%C3%AE-1%C3%A2-4-linked-galactan-side-chains-and-structural-basis-for-its-self-aggregation
#13
Olga N Makshakova, Tatyana A Gorshkova, Polina V Mikshina, Yuriy F Zuev, Serge Perez
Within the family of plant cell wall polysaccharides rhamnogalacturonans I are the most diverse and structurally complex members. In present study we characterize the 3-dimensional structures and dynamic features of the constituents of RG-I along MD trajectories. It is demonstrated that extended threefold helical structure of the rhamnogalacturonan linear backbone is the most energetically favorable motif. Branching helps to stabilize a conformer of the backbone twisted along 1→2 glycosidic linkage triggering the orientation of long side chains without altering the extended overall backbone chain conformation...
February 20, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28017154/advances-in-micelle-based-drug-delivery-cross-linked-systems
#14
İsmail Alper İşoğlu, Yıldız Özsoy, Sevil Dinçer İşoğlu
There are several barriers that drug molecules encounter in body beginning from kidney filtration and reticulo-endothelial system (RES) clearance to cellular trafficking. Multifunctional nanocarriers have a great potential for the delivery of drugs by enhancing therapeutic activity of existing methodologies. A variety of nanocarriers are constructed by different material types, which have unique physicochemical properties for drug delivery applications. Micelles formed by amphiphilic polymers are one of the most important drug/nanocarrier formulation products, in which the core part is suitable for encapsulation of hydrophobic agent whereas the outer shell can be utilized for targeting the drug to the disease area...
December 22, 2016: Current Topics in Medicinal Chemistry
https://www.readbyqxmd.com/read/28013005/effects-of-%C3%AE-sheet-crystals-and-a-glycine-rich-matrix-on-the-thermal-conductivity-of-spider-dragline-silk
#15
Jinju Park, Duckjong Kim, Seung-Mo Lee, Ji-Ung Choi, Myungil You, Hye-Mi So, Junkyu Han, Junghyo Nah, Jae Hun Seol
We measured the thermal conductivity of Araneus ventricosus' spider dragline silk using a suspended microdevice. The thermal conductivity of the silk fiber was approximately 0.4Wm(-1)K(-1) at room temperature and gradually increased with an increasing temperature in a manner similar to that of other disordered crystals or proteins. In order to elucidate the effect of β-sheet crystals in the silk, thermal denaturation was used to reduce the quantity of the β-sheet crystals. A calculation with an effective medium approximation supported this measurement result showing that the thermal conductivity of β-sheet crystals had an insignificant effect on the thermal conductivity of SDS...
December 21, 2016: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/27997792/tethering-an-n-glycosylation-sequon-containing-peptide-creates-a-catalytically-competent-oligosaccharyltransferase-complex
#16
Shunsuke Matsumoto, Yuya Taguchi, Atsushi Shimada, Mayumi Igura, Daisuke Kohda
Oligosaccharyltransferase (OST) transfers an oligosaccharide chain to the Asn residue in the Asn-X-Ser/Thr sequon in proteins, where X is not proline. A sequon was tethered to an archaeal OST enzyme via a disulfide bond. The positions of the cysteine residues in the OST protein and the sequon-containing acceptor peptide were selected by reference to the eubacterial OST structure in a non-covalent complex with an acceptor peptide. We determined the crystal structure of the cross-linked OST-sequon complex. The Ser/Thr-binding pocket recognizes the Thr residue in the sequon, and the catalytic structure referred to as 'carboxylate dyad' interacted with the Asn residue...
December 20, 2016: Biochemistry
https://www.readbyqxmd.com/read/27997545/a-general-method-for-targeted-quantitative-cross-linking-mass-spectrometry
#17
Juan D Chavez, Jimmy K Eng, Devin K Schweppe, Michelle Cilia, Keith Rivera, Xuefei Zhong, Xia Wu, Terrence Allen, Moshe Khurgel, Akhilesh Kumar, Athanasios Lampropoulos, Mårten Larsson, Shuvadeep Maity, Yaroslav Morozov, Wimal Pathmasiri, Mathew Perez-Neut, Coriness Pineyro-Ruiz, Elizabeth Polina, Stephanie Post, Mark Rider, Dorota Tokmina-Roszyk, Katherine Tyson, Debora Vieira Parrine Sant'Ana, James E Bruce
Chemical cross-linking mass spectrometry (XL-MS) provides protein structural information by identifying covalently linked proximal amino acid residues on protein surfaces. The information gained by this technique is complementary to other structural biology methods such as x-ray crystallography, NMR and cryo-electron microscopy[1]. The extension of traditional quantitative proteomics methods with chemical cross-linking can provide information on the structural dynamics of protein structures and protein complexes...
2016: PloS One
https://www.readbyqxmd.com/read/27997116/cross-linked-fluorescent-supramolecular-nanoparticles-as-finite-tattoo-pigments-with-controllable-intradermal-retention-times
#18
Jin-Sil Choi, Yazhen Zhu, Hongsheng Li, Parham Peyda, Thuy Tien Nguyen, Mo Yuan Shen, Yang Michael Yang, Jingyi Zhu, Mei Liu, Mandy M Lee, Shih-Sheng Sun, Yang Yang, Hsiao-Hua Yu, Kai Chen, Gary S Chuang, Hsian-Rong Tseng
Tattooing has been utilized by the medical community for precisely demarcating anatomic landmarks. This practice is especially important for identifying biopsy sites of nonmelanoma skin cancer (NMSC) due to the long interval (i.e., up to 3 months) between the initial diagnostic biopsy and surgical treatment. Commercially available tattoo pigments possess several issues, which include causing poor cosmesis, being mistaken for a melanocytic lesion, requiring additional removal procedures when no longer desired, and potentially inducing inflammatory responses...
December 20, 2016: ACS Nano
https://www.readbyqxmd.com/read/27987759/covalent-and-injectable-chitosan-chondroitin-sulfate-hydrogels-embedded-with-chitosan-microspheres-for-drug-delivery-and-tissue-engineering
#19
Ming Fan, Ye Ma, Huaping Tan, Yang Jia, Siyue Zou, Shuxuan Guo, Meng Zhao, Hao Huang, Zhonghua Ling, Yong Chen, Xiaohong Hu
Injectable hydrogels and microspheres derived from natural polysaccharides have been extensively investigated as drug delivery systems and cell scaffolds. In this study, we report a preparation of covalent hydrogels basing polysaccharides via the Schiff' base reaction. Water soluble carboxymethyl chitosan (CMC) and oxidized chondroitin sulfate (OCS) were prepared for cross-linking of hydrogels. The mechanism of cross-linking is attributed to the Schiff' base reaction between amino and aldehyde groups of polysaccharides...
February 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/27987701/magnetically-modified-bacterial-cellulose-a-promising-carrier-for-immobilization-of-affinity-ligands-enzymes-and-cells
#20
Eva Baldikova, Kristyna Pospiskova, Dimitrios Ladakis, Ioannis K Kookos, Apostolis A Koutinas, Mirka Safarikova, Ivo Safarik
Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was magnetically modified using perchloric acid stabilized magnetic fluid. Magnetic bacterial cellulose (MBC) was used as a carrier for the immobilization of affinity ligands, enzymes and cells. MBC with immobilized reactive copper phthalocyanine dye was an efficient adsorbent for crystal violet removal; the maximum adsorption capacity was 388mg/g. Kinetic and thermodynamic parameters were also determined. Model biocatalysts, namely bovine pancreas trypsin and Saccharomyces cerevisiae cells were immobilized on MBC using several strategies including adsorption with subsequent cross-linking with glutaraldehyde and covalent binding on previously activated MBC using sodium periodate or 1,4-butanediol diglycidyl ether...
February 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
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