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Side chain cross link

Silvia Panzavolta, Paola Torricelli, Sonia Casolari, Annapaola Parrilli, Sofia Amadori, Milena Fini, Adriana Bigi
The systemic administration of bisphosphonates (BPs) for the treatment of metabolic diseases characterized by abnormal bone loss suffers from several adverse side effects, which can be reduced by implementation of alternative modes of administration. In this work, glutaraldehyde cross-linked gelatin scaffolds are proposed as delivery systems of calcium alendronate monohydrate (CaAL•H2 O). The 3D highly porous scaffolds display a relevant interconnected porosity (>94%), independently from CaAL•H2 O content (0, 3, and 6 wt%)...
October 17, 2016: Macromolecular Bioscience
Shyam K Konda, Celine Kelso, Jelena Medan, Brad E Sleebs, Don R Phillips, Suzanne M Cutts, J Grant Collins
The major covalent adduct formed between a (13)C-labelled formaldehyde activated bis-amino mitoxantrone analogue (WEHI-150) and the hexanucleotide d(CG(5Me)CGCG)2 has been isolated by HPLC chromatography and the structure determined by NMR spectroscopy. The results indicate that WEHI-150 forms one covalent bond through a primary amine to the N-2 of the G2 residue, with the polycyclic ring structure intercalated at the (5Me)C3pG4/G10p(5Me)C9 site. Furthermore, the WEHI-150 aromatic ring system is oriented approximately parallel to the long axis of the base pairs, with one aliphatic side-chain in the major groove and the other side-chain in the minor groove...
October 13, 2016: Organic & Biomolecular Chemistry
Nina Bionda, Rudi Fasan
Many biologically active peptides found in nature exhibit a bicyclic structure wherein a head-to-tail cyclic backbone is further constrained by an intramolecular linkage connecting two side chains of the peptide. Accordingly, methods to access macrocyclic peptides sharing this overall topology could be of significant value toward the discovery of new functional entities and bioactive compounds. With this goal in mind, we recently developed a strategy for enabling the biosynthesis of thioether-bridged bicyclic peptides in living bacterial cells...
2017: Methods in Molecular Biology
Chih-Kuang Chen, Wei-Jen Lin, Yu Hsia, Leu-Wei Lo
Well-defined poly(ethylene glycol)-b-allyl functional polylactide-b-polylactides (PEG-APLA-PLAs) are synthesized through sequential ring-opening polymerization. PEG-APLA-PLAs that have amphiphilic properties and reactive allyl side chains on their intermediate blocks are successfully transferred to core-shell interface cross-linked micelles (ICMs) by micellization and UV-initiated irradiation. ICMs have demonstrated enhanced colloidal stability in physiological-mimicking media. Hydrophobic molecules such as Nile Red or doxorubicin (Dox) are readily loaded into ICMs; the resulting drug-ICM formulations possess slow and sustained drug release profiles under physiological-mimicking conditions...
September 28, 2016: Macromolecular Bioscience
Harveen Kaur, Meder Kamalov, Margaret A Brimble
In nature, proteins, lipids, and nucleic acids can nonenzymatically react with sugars and sugar degradation products to give rise to a diverse range of modifications, known as advanced glycation endproducts (AGEs). These AGEs typically occur at lysine and arginine residues of long-lived proteins, such as collagen, and can modify the structure and function of the native protein. AGEs accumulate during the normal aging process, and AGE formation is dramatically accelerated with diabetes. AGEs have also been implicated in a wide range of debilitating conditions including cardiovascular, renal failure, and neurodegenerative diseases...
October 18, 2016: Accounts of Chemical Research
Susith Wickramaratne, Shaofei Ji, Shivam Mukherjee, Yan Su, Matthew G Pence, Lee Lior-Hoffmann, Iwen Fu, Suse Broyde, F Peter Guengerich, Mark Distefano, Orlando D Scharer, Yuk Yin Sham, Natalia Tretyakova
DNA-protein cross-links (DPCs) are bulky DNA lesions that form both endogenously and following exposure to bis-electrophiles such as common antitumor agents. The structural and biological consequences of DPCs have not been fully elucidated due to the complexity of these adducts. The most common site of DPC formation in DNA following treatment with bis-electrophiles such as nitrogen mustards and cisplatin is the N7 position of guanine, but the resulting conjugates are hydrolytically labile and thus are not suitable for structural and biological studies...
September 12, 2016: Journal of Biological Chemistry
Bo Wang, Young Sil Jeon, Ho Seok Park, Ji-Heung Kim
Stimuli-responsive and self-healing materials have a wide range of potential uses, and some significant research has focused on cross-linking of hydrogel materials by means of reversible coordination bonding. The resulting materials, however, tend to have poor mechanical properties with pronounced weakness and brittleness. In this work, we present a novel mussel-inspired graphene oxide(GO)-containing hydrogel based on modified polyaspartamide with γ-amino butyric acid (GABA), 3.4-dihydroxyphenethylamine (DOPA), and ethanolamine (EA), termed PolyAspAm(GABA/DOPA/EA)...
December 1, 2016: Materials Science & Engineering. C, Materials for Biological Applications
Ameya R Narkar, Brett Barker, Matthew Clisch, Jingfeng Jiang, Bruce P Lee
A smart adhesive capable of binding to a wetted surface was prepared by copolymerizing dopamine methacrylamide (DMA) and 3-acrylamido phenylboronic acid (AAPBA). pH was used to control the oxidation state and the adhesive property of the catechol side chain of DMA and to trigger the catechol-boronate complexation. FTIR spectroscopy confirmed the formation of the complex at pH 9, which was not present at pH 3. The formation of the catechol-boronate complex increased the cross-linking density of the adhesive network...
August 9, 2016: Chemistry of Materials: a Publication of the American Chemical Society
David C McLeod, Nicolay V Tsarevsky
Polymers bearing activated aziridine groups are attractive precursors to α-substituted-β-amino-functionalized materials due to the enhanced reactivity of the pendant aziridine functionalities toward ring-opening by nucleophiles. Two aziridine-containing styrenic monomers, 2-(4-vinylphenyl)aziridine (VPA) and N-mesyl-2-(4-vinylphenyl)aziridine (NMVPA), were polymerized under a variety of reversible deactivation radical polymerization conditions. Low-catalyst-concentration atom transfer radical polymerization (LCC-ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization were ineffective at producing well-defined polymers from VPA due to side reactions between the aziridine functionalities and the agents controlling the polymerizations (catalysts or chain transfer agents)...
October 2016: Macromolecular Rapid Communications
S Pyr Dit Ruys, J-M Bonzom, S Frelon
Oxidative stress has been extensively studied due to its correlation with cellular disorders and aging. In proteins, one biomarker of oxidative stress is the presence of carbonyl groups, such as aldehyde and ketone, in specific amino acid side chains such as lysine, proline, arginine and threonine, so-called protein carbonylation (PC). PC study is now a growing field in general and medical science since PC accumulation is associated with various pathologies and disorders. At present, enzyme-linked immunosorbent assays (ELISA) seem to be the most robust method of quantifying the presence of carbonyl groups in proteins, despite having some recognised caveats...
August 10, 2016: Free Radical Biology & Medicine
Wanatchaporn Arunmanee, Monisha Pathania, Alexandra S Solovyova, Anton P Le Brun, Helen Ridley, Arnaud Baslé, Bert van den Berg, Jeremy H Lakey
The outer membrane (OM) of gram-negative bacteria is an unusual asymmetric bilayer with an external monolayer of lipopolysaccharide (LPS) and an inner layer of phospholipids. The LPS layer is rigid and stabilized by divalent cation cross-links between phosphate groups on the core oligosaccharide regions. This means that the OM is robust and highly impermeable to toxins and antibiotics. During their biogenesis, OM proteins (OMPs), which function as transporters and receptors, must integrate into this ordered monolayer while preserving its impermeability...
August 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
Kaho Maeda, Liu Hong, Taishi Nishihara, Yusuke Nakanishi, Yuhei Miyauchi, Ryo Kitaura, Naoki Ousaka, Eiji Yashima, Hideto Ito, Kenichiro Itami
Organic nanotubes (ONTs) are tubular nanostructures composed of small molecules or macromolecules that have found various applications including ion sensor/channels, gas absorption, and photovoltaics. While most ONTs are constructed by self-assembly processes based on weak noncovalent interactions, this unique property gives rise to the inherent instability of their tubular structures. Herein, we report a simple "helix-to-tube" strategy to construct robust, covalent ONTs from easily accessible poly(m-phenylene diethynylene)s (poly-PDEs) possessing chiral amide side chains that can adopt a helical conformation through hydrogen-bonding interactions...
August 31, 2016: Journal of the American Chemical Society
Veronika Ulrich, Madeleine Peschke, Clara Brieke, Max J Cryle
Glycopeptide antibiotic biosynthesis involves a complex cascade of reactions centred on a non-ribosomal peptide synthetase and modifiying proteins acting in trans, such as Cytochrome P450 enzymes. These P450s are responsible for cyclisation of the peptide via cross-linking aromatic amino acid side chains, which are a hallmark of the glycopeptide antibiotics. Here, we analysed the first cyclisation reaction in the biosynthesis of the glycopeptide antibiotic A47934. Our results demonstrate that the P450 StaH is recruited to the NRPS machinery through interaction with the X-domain present in the last A47934 NRPS module...
October 20, 2016: Molecular BioSystems
Hamed Asadi, Sepideh Khoee
Nanosized polymeric delivery systems that encapsulate drug molecules and release them in response to a specific intracellular stimulus are of promising interest for cancer therapy. Here, we demonstrated a simple and fast synthetic protocol of redox-responsive nanogels with high drug encapsulation efficiency and stability. The prepared nanogels displayed narrow size distributions and versatility of surface modification. The polymer precursor of these nanogels is based on a random copolymer that contains oligoethyleneglycol (OEG) and pyridyldisulfide (PDS) units as side-chain functionalities...
September 10, 2016: International Journal of Pharmaceutics
Christoph Hage, Christian H Ihling, Michael Götze, Mathias Schäfer, Andrea Sinz
We have synthesized a homobifunctional amine-reactive cross-linking reagent, containing a TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy) and a benzyl group (Bz), termed TEMPO-Bz-linker, to derive three-dimensional structural information of proteins. The aim for designing this novel cross-linker was to facilitate the mass spectrometric analysis of cross-linked products by free radical initiated peptide sequencing (FRIPS). In an initial study, we had investigated the fragmentation behavior of TEMPO-Bz-derivatized peptides upon collision activation in (+)-electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MS/MS) experiments...
July 14, 2016: Journal of the American Society for Mass Spectrometry
Zhigao Wang, Xinghai Zhang, Fangqiang Wang, Xinsheng Lan, Yiqian Zhou
In order to analyze the cracking and aging reason of the silicone rubber current transformer (CT) insulation bushing used for 8 years from a 500 kV alternating current substation, characteristics including Fourier transform infrared (FTIR) spectroscopy, mechanical properties analysis, hardness, and thermo gravimetric analysis have been carried out. The FTIR results indicated that the external surface of the silicone rubber CT insulation bushing suffered from more serious aging than the internal part, fracture of side chain Si-C bond was much more than the backbone...
2016: SpringerPlus
Marziyeh Haghighat, Quincy Teng, Ruiqin Zhong, Zheng-Hua Ye
Xylan is a major cross-linking hemicellulose in secondary walls of vascular tissues, and the recruitment of xylan as a secondary wall component was suggested to be a pivotal event for the evolution of vascular tissues. To decipher the evolution of xylan structure and xylan biosynthetic genes, we analyzed xylan substitution patterns and characterized genes mediating methylation of glucuronic acid (GlcA) side chains in xylan of the model seedless vascular plant, Selaginella moellendorffii, and investigated GT43 genes from S...
August 2016: Plant & Cell Physiology
Yulia D Gordievskaya, Artem M Rumyantsev, Elena Yu Kramarenko
Conformational behaviour of hydrophobically modified (HM) polymer gels in solutions of nonionic surfactants is studied theoretically. A HM gel contains hydrophobic side chains (stickers) grafted to its subchains. Hydrophobic stickers are capable to aggregate into joint micelles with surfactant molecules. Micelles containing more than one sticker serve as additional physical cross-links of the network, and their formation causes gel shrinking. In the proposed theoretical model, the interior of the gel/surfactant complex is treated as an array of densely packed spherical polymer brushes consisting of gel subchains tethered to the surface of the spherical sticker/surfactant micelles...
May 14, 2016: Journal of Chemical Physics
Simone Stichler, Tomasz Jungst, Martha Schamel, Ilona Zilkowski, Matthias Kuhlmann, Thomas Böck, Torsten Blunk, Jörg Teßmar, Jürgen Groll
In this study we introduce linear poly(glycidol) (PG), a structural analog of poly(ethylene glycol) bearing side chains at each repeating unit, as polymer basis for bioink development. We prepare allyl- and thiol-functional linear PG that can rapidly be polymerized to a three-dimensionally cross-linked hydrogel network via UV mediated thiol-ene click reaction. Influence of polymer concentration and UV irradiation on mechanical properties and swelling behavior was examined. Thiol-functional PG was synthesized in two structural variations, one containing ester groups that are susceptible to hydrolytic cleavage, and the other one ester-free and stable against hydrolysis...
May 13, 2016: Annals of Biomedical Engineering
Ahmed M Abu El-Asrar, Mohammad Mairaj Siddiquei, Mohd Imtiaz Nawaz, Gert De Hertogh, Ghulam Mohammad, Kaiser Alam, Ahmed Mousa, Ghislain Opdenakker
PURPOSE: Heparanase cleaves heparan sulfate side chains of heparan sulfate proteoglycans, activity that is implicated in angiogenesis. Proteolytic cleavage of proheparanase by cathepsin L leads to the formation of catalytically active heparanase. We investigated the expression levels of heparanase enzymatic activity and correlated these with the levels of cathepsin L, the angiogenic factors tissue factor (TF) and matrix metalloproteinase-9 (MMP-9), and the angiostatic factor tissue factor pathway inhibitor (TFPI) in proliferative diabetic retinopathy (PDR)...
2016: Molecular Vision
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