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Covalently cross linked

Anthony Neville, Javier Iniesta, Jose M Palomo
Heterogeneous catalysts have been synthesi zed by the conjugation of Hoveyda-Grubbs second-generation catalyst with a lipase. The catalytic properties of the organometallic compound in solution were firstly optimized, evaluating the activity of Ru in the ring-closing metathesis of diethyldiallymalonate at 25 °C at different solvents and in the presence of different additives. The best result was found using tetrahydrofuran as a solvent. Some additives such as phenylboronic acid or polyetheneglycol slightly improved the activity of the Ru catalyst whereas others, such as pyridine or dipeptides affected it negatively...
December 6, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Kourosh Abdollahi, Farshad Yazdani, Reza Panahi
Preparation and characterization of cross linked amine-functionalized magnetic nanoparticles as an appropriate support for covalent immobilization on tyrosinase was presented in the study "Covalent immobilization of tyrosinase onto cyanuric chloride crosslinked amine-functionalized superparamagnetic nanoparticles: synthesis and characterization of the recyclable nanobiocatalyst" (Abdollahi et al., 2016 ) [1]. Herein, complementary data regarding X-ray powder diffraction (XRD) to characterize the synthesized magnetic nanoparticles, and transmission electron microscopy (TEM) to determine the size and morphology of tyrosinase immobilized magnetic nanoparticles (tyrosinase-MNPs) were reported...
December 2016: Data in Brief
Romain Coriat, Sandrine J Faivre, Olivier Mir, Chantal Dreyer, Stanislas Ropert, Mohammed Bouattour, Robert Desjardins, François Goldwasser, Eric Raymond
BACKGROUND: DTS-108 is a hydrosoluble prodrug, where the SN-38 moiety is covalently linked to a 20-amino acid vector peptide by a specific esterase-sensitive cross-linker, releasing 7-ethyl-10-hydroxycampthotecin (SN-38) by esterase bond cleavage. METHODS: The pharmacokinetics of DTS-108, adverse events graded according to NCI-CTCv3.1, dose-limiting toxicities at cycle 1, the maximum tolerated dose (MTD), and the recommended Phase II dose (RP2D) of intravenous DTS-108 (1-2 hours) every 2 weeks were evaluated in a first-in-human Phase I study in patients with advanced/metastatic carcinomas, according to an accelerated dose escalation design...
2016: International Journal of Nanomedicine
Barbara S Janović, Milica Lj Mićić Vićovac, Zoran M Vujčić, Miroslava T Vujčić
Peroxidases (EC have enormous biotechnological applications. Usage of more abundant, basic isoforms of peroxidases in diagnostic kits and/or in immunochemistry has led to under exploitation and disregard of horseradish peroxidase (HRP) acidic isoforms. Therefore, acidic horseradish peroxidase (HRP-A) isoenzyme was used for the preparation of a biocatalyst with improved ability in dye decolorization. Ten biocatalysts were prepared by covalent binding of enzyme to chitosan and alginate, adsorption followed by cross-linking on inorganic support (aluminum oxide), and encapsulation in spherical calcium alginate beads via polyethylene glycol...
December 1, 2016: Environmental Science and Pollution Research International
Faiza Shahid, Afsheen Aman, Muhammad Asif Nawaz, Asad Karim, Shah Ali Ul Qader
Dextranase is a unique biocatalyst that has high specificity and stereo-selectivity towards a complex biopolymer known as dextran. Dextranase has wide industrial application, but most of the time harsh environmental conditions adversely affect the functionality and stability of the enzyme. To overcome this issue, a covalent cross-linking immobilization method was adapted in the current study utilizing a nontoxic and biocompatible matrix known as chitosan. Chitosan hydrogel microspheres were synthesized using chitosan which exhibited noteworthy physical and mechanical strength...
November 30, 2016: Bioprocess and Biosystems Engineering
Toshiaki Nakano, Xu Xu, Amir M H Salem, Mahmoud I Shoulkamy, Hiroshi Ide
Ionizing radiation produces various DNA lesions such as base damage, DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and DNA-protein cross-links (DPCs). Of these, the biological significance of DPCs remains elusive. In this article, we focus on radiation-induced DPCs and review the current understanding of their induction, properties, repair, and biological consequences. When cells are irradiated, the formation of base damage, SSBs, and DSBs are promoted in the presence of oxygen. Conversely, that of DPCs is promoted in the absence of oxygen, suggesting their importance in hypoxic cells, such as those present in tumors...
November 25, 2016: Free Radical Biology & Medicine
Paul J M Jackson, Khondaker M Rahman, David E Thurston
The pyrrolobenzodiazepine (PBD) and duocarmycin families are DNA-interactive agents that covalently bond to guanine (G) and adenine (A) bases, respectively, and that have been joined together to create synthetic dimers capable of cross-linking G-G, A-A, and G-A bases. Three G-A alkylating dimers have been reported in publications to date, with defined DNA-binding sites proposed for two of them. In this study we have used molecular dynamics simulations to elucidate preferred DNA-binding sites for the three published molecular types...
October 12, 2016: Bioorganic & Medicinal Chemistry Letters
D K O'Flaherty, C J Wilds
A methodology is reported to conjugate human O(6)-alkylguanine-DNA-alkyltransferase (hAGT) to the 3'-end of DNA in excellent yields with short reaction times by using intrastrand cross-linked (IaCL) DNA probes. This strategy exploited the substrate specificity of hAGT to generate the desired DNA-protein covalent complex. IaCL DNA linking two thymidine residues, or linking a thymidine residue to a 2'-deoxyguanosine residue (either in a 5'→3' or 3'→5' fashion), lacking a phosphodiester linkage at the cross-linked site, were prepared using a phosphoramidite strategy followed by solid-phase synthesis...
November 25, 2016: Organic & Biomolecular Chemistry
Cindy Strehl, Lionel Maurizi, Timo Gaber, Paula Hoff, Thomas Broschard, A Robin Poole, Heinrich Hofmann, Frank Buttgereit
Combined individually tailored methods for diagnosis and therapy (theragnostics) could be beneficial in destructive diseases, such as rheumatoid arthritis. Nanoparticles are promising candidates for theragnostics due to their excellent biocompatibility. Nanoparticle modifications, such as improved surface coating, are in development to meet various requirements, although safety concerns mean that modified nanoparticles require further review before their use in medical applications is permitted. We have previously demonstrated that iron oxide nanoparticles with amino-polyvinyl alcohol (a-PVA) adsorbed on their surfaces have the unwanted effect of increasing human immune cell cytokine secretion...
2016: International Journal of Nanomedicine
Fernando Rodriguez-Pascual, David Anthony Slatter
Collagens constitute a large family of extracellular matrix (ECM) proteins that play a fundamental role in supporting the structure of various tissues in multicellular animals. The mechanical strength of fibrillar collagens is highly dependent on the formation of covalent cross-links between individual fibrils, a process initiated by the enzymatic action of members of the lysyl oxidase (LOX) family. Fibrillar collagens are present in a wide variety of animals, therefore often being associated with metazoan evolution, where the emergence of an ancestral collagen chain has been proposed to lead to the formation of different clades...
November 23, 2016: Scientific Reports
Marlies A Lambrecht, Ine Rombouts, Mieke A Nivelle, Jan A Delcour
Noodles of constant protein content and flour-to-egg protein ratio were made with whole egg, egg white, or egg yolk. The optimal cooking time, water absorption, and cooking loss of salted whole egg noodles was respectively lower and higher than of egg white and egg yolk noodles. However, cooked whole egg noodles showed the best Kieffer-rig extensibility. Differences in noodle properties were linked to protein network formation. Disulfide bonds in whole egg noodles developed faster and to a larger extent during cooking than in egg yolk noodles but slower and to a lower extent than in egg white noodles...
November 22, 2016: Journal of Food Science
Ferenc Bánáti, Kálmán Szenthe
Chromatin Immunoprecipitation (ChIP) is a method used to detect DNA-protein interactions in vivo. ChIP has been widely applied to assess the abundance of various epigenetic regulators, including modified histones, in various regions of cellular and viral chromatin. During the procedure, DNA binding proteins are covalently cross-linked to DNA, and the isolated chromatin is broken into pieces of 300-500 bps in length on average. Thereafter, using specific antibody directed against the protein of interest the covalently cross-linked DNA is pulled down together with Protein A or G carrying beads that bind the Fc fragment of the antibody...
2017: Methods in Molecular Biology
Faezeh Moghadam Ariaee, Maryam Hashemi, Sara Amel Farzad, Khalil Abnous, Mohammad Ramezani
OBJECTIVES: In recent years, polypropyleneimine (PPI) dendrimers have attracted great interest as non-viral gene delivery systems because of their attractive features including highly branched architecture with number of reactive end groups. However, without being structurally modified, they are not efficient gene carriers. In the present study, generation 2 and 3 (G2 and G3) of PPI dendrimers were conjugated with alkylcarboxylate groups as linker to enhance the transfection efficiency while maintaining their low cell toxicity...
October 2016: Iranian Journal of Basic Medical Sciences
Paolo Zucca, Roberto Fernandez-Lafuente, Enrico Sanjust
Agarose is a polysaccharide obtained from some seaweeds, with a quite particular structure that allows spontaneous gelation. Agarose-based beads are highly porous, mechanically resistant, chemically and physically inert, and sharply hydrophilic. These features-that could be further improved by means of covalent cross-linking-render them particularly suitable for enzyme immobilization with a wide range of derivatization methods taking advantage of chemical modification of a fraction of the polymer hydroxyls...
November 19, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Ievgen Shulov, Roman V Rodik, Youri Arntz, Andreas Reisch, Vitaly I Kalchenko, Andrey S Klymchenko
The key challenge in the field of fluorescent nanoparticles (NPs) for biological applications is to achieve superior brightness for sizes equivalent to single proteins (3-7 nm). We propose a concept of shell-cross-linked fluorescent micelles, in which PEGylated cyanine 3 and 5 bis-azides form a covalently attached corona on micelles of amphiphilic calixarene bearing four alkyne groups. The fluorescence quantum yield of the obtained monodisperse NPs, with a size of 7 nm, is a function of viscosity and reached up to 15 % in glycerol...
November 16, 2016: Angewandte Chemie
Elena Kudryashova, David B Heisler, Dmitri S Kudryashov
Actin cross-linking toxins are produced by Gram-negative bacteria from Vibrio and Aeromonas genera. The toxins were named actin cross-linking domains (ACD), since the first and most of the subsequently discovered ACDs were found as effector domains in larger MARTX and VgrG toxins. Among recognized human pathogens, ACD is produced by Vibrio cholerae, Vibrio vulnificus, and Aeromonas hydrophila. Upon delivery to the cytoplasm of a host cell, ACD covalently cross-links actin monomers into non-polymerizable actin oligomers of various lengths...
November 18, 2016: Current Topics in Microbiology and Immunology
Sungmin Nam, Joanna Lee, Doug G Brownfield, Ovijit Chaudhuri
Living tissues consist largely of cells and extracellular matrices (ECMs). The mechanical properties of ECM have been found to play a key role in regulating cell behaviors such as migration, proliferation, and differentiation. Although most studies to date have focused on elucidating the impact of matrix elasticity on cell behaviors, recent studies have revealed an impact of matrix viscoelasticity on cell behaviors and reported plastic remodeling of ECM by cells. In this study, we rigorously characterized the plasticity in materials commonly used for cell culture...
November 15, 2016: Biophysical Journal
Ayami Kita, Nobumasa Hino, Sakiko Higashi, Kohji Hirota, Ryohei Narumi, Jun Adachi, Kazuaki Takafuji, Kenji Ishimoto, Yoshiaki Okada, Kensaku Sakamoto, Takeshi Tomonaga, Seiji Takashima, Hiroyuki Mizuguchi, Takefumi Doi
The site-specific incorporation of cross-linkable designer amino acids into proteins is useful for covalently bonding protein complexes upon exposure to light. This technology can be used to study networks of protein-protein interactions in living cells; however, to date it has only been applicable for use with a narrow range of cell types, due to the limited availability of plasmid-based transfection protocols. In the present study, we achieved adenovirus-based expression of a variant of an archaeal pyrrolysyl-tRNA synthetase and UAG-recognising tRNA pair, which was used to incorporate unnatural amino acids into proteins at sites defined by in-frame UAG codons within genes...
November 11, 2016: Scientific Reports
Sarwat Jamil, Payman Hojabrpour, Vincent Duronio
p53 is a tumor suppressor protein which is either lost or inactivated in a large majority of tumors. The small molecule 2-phenylethynesulfonamide (PES) was originally identified as the inhibitor of p53 effects on the mitochondrial death pathway. In this report we demonstrate that p53 protein from PES-treated cells was detected in reduced mobility bands between molecular weights 95-220 kDa. Resolution of p53 aggregates on urea gel was unable to reduce the high molecular weight p53 aggregates, which were shown to be primarily located in the nucleus...
November 7, 2016: Biochemical and Biophysical Research Communications
Jan Michels, Esther Appel, Stanislav N Gorb
Resilin is an elastomeric protein typically occurring in exoskeletons of arthropods. It is composed of randomly orientated coiled polypeptide chains that are covalently cross-linked together at regular intervals by the two unusual amino acids dityrosine and trityrosine forming a stable network with a high degree of flexibility and mobility. As a result of its molecular prerequisites, resilin features exceptional rubber-like properties including a relatively low stiffness, a rather pronounced long-range deformability and a nearly perfect elastic recovery...
2016: Beilstein Journal of Nanotechnology
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