@article{MichalikOnichimowskaKernRiedeletal.2017, author = {Michalik-Onichimowska, Aleksandra and Kern, Simon and Riedel, Jens and Panne, Ulrich and King, Rudibert and Maiwald, Michael}, title = {"Click" analytics for "click" chemistry - A simple method for calibration-free evaluation of online NMR spectra}, series = {Journal of magnetic resonance}, volume = {277}, journal = {Journal of magnetic resonance}, publisher = {Elsevier}, address = {San Diego}, issn = {1090-7807}, doi = {10.1016/j.jmr.2017.02.018}, pages = {154 -- 161}, year = {2017}, abstract = {Driven mostly by the search for chemical syntheses under biocompatible conditions, so called "click" chemistry rapidly became a growing field of research. The resulting simple one-pot reactions are so far only scarcely accompanied by an adequate optimization via comparably straightforward and robust analysis techniques possessing short set-up times. Here, we report on a fast and reliable calibration-free online NMR monitoring approach for technical mixtures. It combines a versatile fluidic system, continuous-flow measurement of H-1 spectra with a time interval of 20 s per spectrum, and a robust, fully automated algorithm to interpret the obtained data. As a proof-of-concept, the thiol-ene coupling between N-boc cysteine methyl ester and ally] alcohol was conducted in a variety of non-deuterated solvents while its time-resolved behaviour was characterized with step tracer experiments. Overlapping signals in online spectra during thiol-ene coupling could be deconvoluted with a spectral model using indirect hard modeling and were subsequently converted to either molar ratios (using a calibration free approach) or absolute concentrations (using 1-point calibration). For various solvents the kinetic constant k for pseudo-first order reaction was estimated to be 3.9 h(-1) at 25 degrees C. The obtained results were compared with direct integration of non-overlapping signals and showed good agreement with the implemented mass balance. (C) 2017 Elsevier Inc. All rights reserved.}, language = {en} } @article{VishnevetskayaHildebrandNiebuuretal.2017, author = {Vishnevetskaya, Natalya S. and Hildebrand, Viet and Niebuur, Bart-Jan and Grillo, Isabelle and Filippov, Sergey K. and Laschewsky, Andre and M{\"u}ller-Buschbaum, Peter and Papadakis, Christine M.}, title = {"Schizophrenic" Micelles from Doubly Thermoresponsive Polysulfobetaine-b-poly(N-isopropylmethacrylamide) Diblock Copolymers}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {50}, journal = {Macromolecules : a publication of the American Chemical Society}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/acs.macromol.7b00356}, pages = {3985 -- 3999}, year = {2017}, language = {en} } @misc{KoenigKellingSchildeetal.2017, author = {K{\"o}nig, Jana and Kelling, Alexandra and Schilde, Uwe and Strauch, Peter}, title = {[µ2-O,O′,Oʺ,Oʺ′-Bis(1,2-dithiooxalato-S,S′)nickel(II)]bis[-O,O′-bis(1,2-dithiooxalato-S,S′)-nickel(II)pentaquaholmium(III)]hydrate, [Ho2Ni3(dto)6(H2O)10]}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400598}, pages = {5}, year = {2017}, abstract = {Planar bis(1,2-dithiooxalato)nickelate(II), [Ni(dto)]2- reacts in aqueous solutions with lanthanide ions (Ln3+) to form pentanuclear, hetero-bimetallic complexes of the general composition [{Ln(H2O)n}2{Ni(dto)2}3]·xH2O. (n = 4 or 5; x = 9-12). The complex [{Ho(H2O)5}2{Ni(dto)2}3]·10H2O, Ho2Ni3, was synthesized and characterized by single crystal X-ray structure analysis and powder diffraction. The Ho2Ni3 complex crystallizes as monoclinic crystals in the space group P21/c. The channels and cavities, appearing in the crystal packing of the complex molecules, are occupied by a varying amount of non-coordinated water molecules.}, language = {en} } @article{MeynersMertensWessigetal.2017, author = {Meyners, Christian and Mertens, Monique and Wessig, Pablo and Meyer-Almes, Franz-Josef}, title = {A Fluorescence-Lifetime-Based Binding Assay for Class IIa Histone Deacetylases}, series = {Chemistry - a European journal}, volume = {23}, journal = {Chemistry - a European journal}, number = {13}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201605140}, pages = {3107 -- 3116}, year = {2017}, abstract = {Class IIa histone deacetylases (HDACs) show extremely low enzymatic activity and no commonly accepted endogenous substrate is known today. Increasing evidence suggests that these enzymes exert their effect rather through molecular recognition of acetylated proteins and recruiting other proteins like HDAC3 to the desired target location. Accordingly, class IIa HDACs like bromodomains have been suggested to act as "Readers" of acetyl marks, whereas enzymatically active HDACs of class I or IIb are called "Erasers" to highlight their capability to remove acetyl groups from acetylated histones or other proteins. Small-molecule ligands of class IIa histone deacetylases (HDACs) have gained tremendous attention during the last decade and have been suggested as pharmaceutical targets in several indication areas such as cancer, Huntington's disease and muscular atrophy. Up to now, only enzyme activity assays with artificial chemically activated trifluoroacetylated substrates are in use for the identification and characterization of new active compounds against class IIa HDACs. Here, we describe the first binding assay for this class of HDAC enzymes that involves a simple mix-and-measure procedure and an extraordinarily robust fluorescence lifetime readout based on [1,3]dioxolo[4,5-f]benzodioxole-based ligand probes. The principle of the assay is generic and can also be transferred to class I HDAC8.}, language = {en} } @article{RackwitzRankovićMilosavljevićetal.2017, author = {Rackwitz, Jenny and Ranković, Miloš Lj. and Milosavljević, Aleksandar R. and Bald, Ilko}, title = {A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides}, series = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, volume = {71}, journal = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, publisher = {Springer}, address = {New York}, issn = {1434-6060}, doi = {10.1140/epjd/e2016-70608-4}, pages = {9}, year = {2017}, abstract = {Low-energy electrons (LEEs) play an important role in DNA radiation damage. Here we present a method to quantify LEE induced strand breakage in well-defined oligonucleotide single strands in terms of absolute cross sections. An LEE irradiation setup covering electron energies <500 eV is constructed and optimized to irradiate DNA origami triangles carrying well-defined oligonucleotide target strands. Measurements are presented for 10.0 and 5.5 eV for different oligonucleotide targets. The determination of absolute strand break cross sections is performed by atomic force microscopy analysis. An accurate fluence determination ensures small margins of error of the determined absolute single strand break cross sections sigma SSB. In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil (U-5F) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of U-5F containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons.}, language = {en} } @article{LorenzSaalfrank2017, author = {Lorenz, U. and Saalfrank, Peter}, title = {A novel system-bath Hamiltonian for vibration-phonon coupling}, series = {Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature}, volume = {482}, journal = {Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature}, publisher = {Elsevier Science}, address = {Amsterdam}, issn = {0301-0104}, doi = {10.1016/j.chemphys.2016.06.004}, pages = {69 -- 80}, year = {2017}, abstract = {We present a rigorous method to set up a system-bath Hamiltonian for the coupling of adsorbate vibrations (the system) to surface phonons (the bath). The Hamiltonian is straightforward to derive and exact up to second order in the environment coordinates, thus capable of treating one- and two-phonon contributions to vibration-phonon coupling. The construction of the Hamiltonian uses orthogonal coordinates for system and bath modes, is based on an embedded cluster approach, and generalizes previous Hamiltonians of a similar type, but avoids several (additional) approximations. While the parametrization of the full Hamiltonian is in principle feasible by a first principles quantum mechanical treatment, here we adopt in the spirit of a QM/MM model a combination of density functional theory ("QM", for the system) and a semiempirical forcefield ("MM", for the bath). We apply the Hamiltonian to a fully H-covered Si(100)-(2 × 1) surface, using Fermi's Golden Rule to obtain vibrational relaxation rates of various H-Si bending modes of this system. As in earlier work it is found that the relaxation is dominated by two-phonon contributions because of an energy gap between the Si-H bending modes and the Si phonon bands. We obtain vibrational lifetimes (of the first excited state) on the order of 2 ps at K. The lifetimes depend only little on the type of bending mode (symmetric vs. antisymmetric, parallel vs. perpendicular to the Si2H2 dimers). They decrease by a factor of about two when heating the surface to 300 K. We also study isotope effects by replacing adsorbed H atoms by deuterium, D. The Si-D bending modes are shifted into the Si phonon band of the solid, opening up one-phonon decay channels and reducing the lifetimes to few hundred fs.}, language = {en} } @article{ThierbachNeissGallandietal.2017, author = {Thierbach, Adrian and Neiss, Christian and Gallandi, Lukas and Marom, Noa and Koerzdoerfer, Thomas and Goerling, Andreas}, title = {Accurate Valence Ionization Energies from Kohn-Sham Eigenvalues with the Help of Potential Adjustors}, series = {Journal of chemical theory and computation}, volume = {13}, journal = {Journal of chemical theory and computation}, publisher = {American Chemical Society}, address = {Washington}, issn = {1549-9618}, doi = {10.1021/acs.jctc.7b00490}, pages = {4726 -- 4740}, year = {2017}, abstract = {An accurate yet computationally very efficient and formally well justified approach to calculate molecular ionization potentials is presented and tested. The first as well as higher ionization potentials are obtained as the negatives of the Kohn-Sham eigenvalues of the neutral molecule after adjusting the eigenvalues by a recently [Gorling Phys. Rev. B 2015, 91, 245120] introduced potential adjustor for exchange-correlation potentials. Technically the method is very simple. Besides a Kohn-Sham calculation of the neutral molecule, only a second Kohn-Sham calculation of the cation is required. The eigenvalue spectrum of the neutral molecule is shifted such that the negative of the eigenvalue of the highest occupied molecular orbital equals the energy difference of the total electronic energies of the cation minus the neutral molecule. For the first ionization potential this simply amounts to a Delta SCF calculation. Then, the higher ionization potentials are obtained as the negatives of the correspondingly shifted Kohn-Sham eigenvalues. Importantly, this shift of the Kohn-Sham eigenvalue spectrum is not just ad hoc. In fact, it is formally necessary for the physically correct energetic adjustment of the eigenvalue spectrum as it results from ensemble density-functional theory. An analogous approach for electron affinities is equally well obtained and justified. To illustrate the practical benefits of the approach, we calculate the valence ionization energies of test sets of small- and medium-sized molecules and photoelectron spectra of medium-sized electron acceptor molecules using a typical semilocal (PBE) and two typical global hybrid functionals (B3LYP and PBE0). The potential adjusted B3LYP and PBE0 eigenvalues yield valence ionization potentials that are in very good agreement with experimental values, reaching an accuracy that is as good as the best G(0)W(0) methods, however, at much lower computational costs. The potential adjusted PBE eigenvalues result in somewhat less accurate ionization energies, which, however, are almost as accurate as those obtained from the most commonly used G(0)W(0) variants.}, language = {en} } @article{AbouserieZehbeMetzneretal.2017, author = {Abouserie, Ahed and Zehbe, Kerstin and Metzner, Philipp and Kelling, Alexandra and G{\"u}nter, Christina and Schilde, Uwe and Strauch, Peter and K{\"o}rzd{\"o}rfer, Thomas and Taubert, Andreas}, title = {Alkylpyridinium Tetrahalidometallate Ionic Liquids and Ionic Liquid Crystals: Insights into the Origin of Their Phase Behavior}, series = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, journal = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-1948}, doi = {10.1002/ejic.201700826}, pages = {5640 -- 5649}, year = {2017}, abstract = {Six N-alkylpyridinium salts [CnPy](2)[MCl4] (n = 4 or 12 and M = Co, Cu, Zn) were synthesized, and their structure and thermal properties were studied. The [C4Py](2)[MCl4] compounds are monoclinic and crystallize in the space group P2(1)/n. The crystals of the longer chain analogues [C12Py](2)[MCl4] are triclinic and crystallize in the space group P (1) over bar. Above the melting temperature, all compounds are ionic liquids (ILs). The derivatives with the longer C12 chain exhibit liquid crystallinity and the shorter chain compounds only show a melting transition. Consistent with single-crystal analysis, electron paramagnetic resonance spectroscopy suggests that the [CuCl4](2-) ions in the Cu-based ILs have a distorted tetrahedral geometry.}, language = {en} } @article{AbouserieZehbeMetzneretal.2017, author = {Abouserie, Ahed and Zehbe, Kerstin and Metzner, Philipp and Kelling, Alexandra and G{\"u}nter, Christina and Schilde, Uwe and Strauch, Peter and K{\"o}rzd{\"o}rfer, Thomas and Taubert, Andreas}, title = {Alkylpyridinium Tetrahalidometallate Ionic Liquids and Ionic Liquid Crystals: Insights into the Origin of Their Phase Behavior}, series = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, journal = {European journal of inorganic chemistry : a journal of ChemPubSoc Europe}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-1948}, doi = {10.1002/ejic.201700826}, pages = {5640 -- 5649}, year = {2017}, abstract = {Six N-alkylpyridinium salts [CnPy](2)[MCl4] (n = 4 or 12 and M = Co, Cu, Zn) were synthesized, and their structure and thermal properties were studied. The [C4Py](2)[MCl4] compounds are monoclinic and crystallize in the space group P2(1)/n. The crystals of the longer chain analogues [C12Py](2)[MCl4] are triclinic and crystallize in the space group P (1) over bar. Above the melting temperature, all compounds are ionic liquids (ILs). The derivatives with the longer C12 chain exhibit liquid crystallinity and the shorter chain compounds only show a melting transition. Consistent with single-crystal analysis, electron paramagnetic resonance spectroscopy suggests that the [CuCl4](2-) ions in the Cu-based ILs have a distorted tetrahedral geometry.}, language = {en} } @article{LutzeBanaresPitaetal.2017, author = {Lutze, Jana and Ba{\~n}ares, Miguel A. and Pita, Marcos and Haase, Andrea and Luch, Andreas and Taubert, Andreas}, title = {alpha-((4-Cyanobenzoyl)oxy)-omega-methyl poly(ethylene glycol)}, series = {Beilstein journal of nanotechnology}, volume = {8}, journal = {Beilstein journal of nanotechnology}, publisher = {Beilstein-Institut zur F{\"o}rderung der Chemischen Wissenschaften}, address = {Frankfurt, Main}, issn = {2190-4286}, doi = {10.3762/bjnano.8.67}, pages = {627 -- 635}, year = {2017}, abstract = {The article describes the synthesis and properties of alpha-((4-cyanobenzoyl)oxy)-omega-methyl poly(ethylene glycol), the first poly(ethylene glycol) stabilizer for metal nanoparticles that is based on a cyano rather than a thiol or thiolate anchor group. The silver particles used to evaluate the effectiveness of the new stabilizer typically have a bimodal size distribution with hydrodynamic diameters of ca. 13 and ca. 79 nm. Polymer stability was evaluated as a function of the pH value both for the free stabilizer and for the polymers bound to the surface of the silver nanoparticles using H-1 NMR spectroscopy and zeta potential measurements. The polymer shows a high stability between pH 3 and 9. At pH 12 and higher the polymer coating is degraded over time suggesting that alpha-((4-cyanobenzoyl) oxy)-omega-methyl poly(ethylene glycol) is a good stabilizer for metal nanoparticles in aqueous media unless very high pH conditions are present in the system. The study thus demonstrates that cyano groups can be viable alternatives to the more conventional thiol/thiolate anchors.}, language = {en} } @article{SchmidtKorbAbell2017, author = {Schmidt, Marco F. and Korb, Oliver and Abell, Chris}, title = {Antagonists of the miRNA-Argonaute 2 Protein Complex}, series = {Drug Target miRNA: Methods and Protocols}, volume = {1517}, journal = {Drug Target miRNA: Methods and Protocols}, publisher = {Springer}, address = {New York}, isbn = {978-1-4939-6563-2}, issn = {1064-3745}, doi = {10.1007/978-1-4939-6563-2_17}, pages = {239 -- 249}, year = {2017}, abstract = {microRNAs (miRNAs) have been identified as high-value drug targets. A widely applied strategy in miRNA inhibition is the use of antisense agents. However, it has been shown that oligonucleotides are poorly cell permeable because of their complex chemical structure and due to their negatively charged backbone. Consequently, the general application of oligonucleotides in therapy is limited. Since miRNAs' functions are executed exclusively by the Argonaute 2 protein, we therefore describe a protocol for the design of a novel miRNA inhibitor class: antagonists of the miRNA-Argonaute 2 protein complex, so-called anti-miR-AGOs, that not only block the crucial binding site of the target miRNA but also bind to the protein's active site. Due to their lower molecular weight and, thus, more drug-like chemical structure, the novel inhibitor class may show better pharmacokinetic properties than reported oligonucleotide inhibitors, enabling them for potential therapeutic use.}, language = {en} } @article{SelemaniNondoMoshietal.2017, author = {Selemani, Ramadhani Selemani Omari and Nondo, Omari and Moshi, Mainen Julius and Erasto, Paul and Masimba, Pax Jessey and Machumi, Francis and Kidukuli, Abdul Waziri and Heydenreich, Matthias and Zofou, Denis}, title = {Anti-plasmodial activity of Norcaesalpin D and extracts of four medicinal plants used traditionally for treatment of malaria}, series = {BMC Complementary and Alternative Medicine volume}, volume = {17}, journal = {BMC Complementary and Alternative Medicine volume}, publisher = {BioMed Central}, address = {London}, issn = {1472-6882}, doi = {10.1186/s12906-017-1673-8}, pages = {8}, year = {2017}, abstract = {Background: Malaria is an old life-threatening parasitic disease that is still affecting many people, mainly children living in sub-Saharan Africa. Availability of effective antimalarial drugs played a significant role in the treatment and control of malaria. However, recent information on the emergence of P. falciparum parasites resistant to one of the artemisinin-based combination therapies suggests the need for discovery of new drug molecules. Therefore, this study aimed to evaluate the antiplasmodial activity of extracts, fractions and isolated compound from medicinal plants traditionally used in the treatment of malaria in Tanzania. Methods: Dry powdered plant materials were extracted by cold macerations using different solvents. Norcaesalpin D was isolated by column chromatography from dichloromethane root extract of Caesalpinia bonducella and its structure was assigned based on the spectral data. Crude extracts, fractions and isolated compound were evaluated for antiplasmodial activity against chloroquine-sensitive P. falciparum (3D7), chloroquine-resistant P. falciparum (Dd2, K1) and artemisinin-resistant P. falciparum (IPC 5202 Battambang, IPC 4912 Mondolkiri) strains using the parasite lactate dehydrogenase assay. Results: The results indicated that extracts of Erythrina schliebenii, Holarrhena pubescens, Dissotis melleri and C. bonducella exhibited antiplasmodial activity against Dd2 parasites. Ethanolic root extract of E. schliebenii had an IC50 of 1.87 mu g/mL while methanolic and ethanolic root extracts of H. pubescens exhibited an IC50 = 2.05 mu g/mL and IC50 = 2.43 mu g/mL, respectively. Fractions from H. pubescens and C. bonducella roots were found to be highly active against K1, Dd2 and artemisinin-resistant parasites. Norcaesalpin D from C. bonducella root extract was active with IC50 of 0.98, 1.85 and 2.13 mu g/mL against 3D7, Dd2 and IPC 4912-Mondolkiri parasites, respectively. Conclusions: Antiplasmodial activity of norcaesalpin D and extracts of E. schliebenii, H. pubescens, D. melleri and C. bonducella reported in this study requires further attention for the discovery of antimalarial lead compounds for future drug development.}, language = {en} } @article{MuthauraKerikoMutaietal.2017, author = {Muthaura, Charles N. and Keriko, Joseph M. and Mutai, Charles and Yenesew, Abiy and Heydenreich, Matthias and Atilaw, Yoseph and Gathirwa, Jeremiah W. and Irungu, Beatrice N. and Derese, Solomon}, title = {Antiplasmodial, cytotoxicity and phytochemical constituents of four maytenus species used in traditional medicine in Kenya}, series = {The natural products journal}, volume = {7}, journal = {The natural products journal}, number = {2}, publisher = {Bentham Science Publ.}, address = {Sharjah}, issn = {2210-3155}, doi = {10.2174/2210315507666161206144050}, pages = {144 -- 152}, year = {2017}, abstract = {Background: In Kenya, several species of the genus Maytenus are used in traditional medicine to treat many diseases including malaria. In this study, phytochemical constituents and extracts of Maytenus undata, M. putterlickioides, M. senegalensis and M. heterophylla were evaluated to determine compound/s responsible for antimalarial activity. Objective: To isolate antiplasmodial compounds from these plant species which could be used as marker compounds in the standardization of their extracts as a phytomedicine for malaria. Methods: Constituents were isolated through activity-guided fractionation of the MeOH/CHCl3 (1:1) extracts and in vitro inhibition of Plasmodium falciparum. Cytotoxicity was evaluated using Vero cells and the compounds were elucidated on the basis of NMR spectroscopy. Results: Fractionation of the extracts resulted in the isolation of ten known compounds. Compound 1 showed promising antiplasmodial activity with IC50, 3.63 and 3.95 ng/ml against chloroquine sensitive (D6) and resistant (W2) P. falciparum, respectively and moderate cytotoxicity (CC50, 37.5 ng/ml) against Vero E6 cells. The other compounds showed weak antiplasmodial (IC50 > 1.93 mu g/ml) and cytotoxic (CC50 > 39.52 mu g/ml) activities against P. falciparum and Vero E6 cells, respectively. Conclusion: (20 alpha)-3-hydroxy-2-oxo-24-nor-friedela-1(10),3,5,7-tetraen-carboxylic acid-(29)-methyl-ester (pristimerin) (1) was the most active marker and lead compound that warrants further investigation as a template for the development of new antimalarial drugs. Pristimerin is reported for the first time in M. putterlickioides. 3-Hydroxyolean-12-en-28-oic acid (oleanolic acid) (5), stigmast-5-en-3-ol (beta-sitosterol) (6), 3-oxo-28-friedelanoic acid (7), olean-12-en-3-ol (beta-amyrin) (8), lup-20(29)-en-3-ol (lupeol) (9) and lup-20(29)-en-3-one (lupenone) (10) are reported for the first time in M. undata.}, language = {en} } @article{KlaussConradHille2017, author = {Klauß, Andr{\´e} and Conrad, Florian and Hille, Carsten}, title = {Binary phase masks for easy system alignment and basic aberration sensing with spatial light modulators in STED microscopy}, series = {Scientific reports}, volume = {7}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-017-15967-5}, pages = {11}, year = {2017}, language = {en} } @article{ZhangBisterfeldBramskietal.2017, author = {Zhang, Shuhao and Bisterfeld, Carolin and Bramski, Julia and Vanparijs, Nane and De Geest, Bruno G. and Pietruszka, J{\"o}rg and B{\"o}ker, Alexander and Reinicke, Stefan}, title = {Biocatalytically Active Thin Films via Self-Assembly of 2-Deoxy-D-ribose-5-phosphate Aldolase-Poly(N-isopropylacrylamide) Conjugates}, series = {Bioconjugate chemistry}, volume = {29}, journal = {Bioconjugate chemistry}, number = {1}, publisher = {American Chemical Society}, address = {Washington}, issn = {1043-1802}, doi = {10.1021/acs.bioconjchem.7b00645}, pages = {104 -- 116}, year = {2017}, abstract = {2-Deoxy-D-ribose-5-phosphate aldolase (DERA) is a biocatalyst that is capable of converting acetaldehyde and a second aldehyde as acceptor into enantiomerically pure mono- and diyhydroxyaldehydes, which are important structural motifs in a number of pharmaceutically active compounds. However, substrate as well as product inhibition requires a more-sophisticated process design for the synthesis of these motifs. One way to do so is to the couple aldehyde conversion with transport processes, which, in turn, would require an immobilization of the enzyme within a thin film that can be deposited on a membrane support. Consequently, we developed a fabrication process for such films that is based on the formation of DERA-poly(N-isopropylacrylamide) conjugates that are subsequently allowed to self-assemble at an air-water interface to yield the respective film. In this contribution, we discuss the conjugation conditions, investigate the interfacial properties of the conjugates, and, finally, demonstrate a successful film formation under the preservation of enzymatic activity.}, language = {en} } @misc{HardyTorresRendonLealEganaetal.2017, author = {Hardy, John G. and Torres-Rendon, Jose Guillermo and Leal-Ega{\~n}a, Aldo and Walther, Andreas and Schlaad, Helmut and C{\"o}lfen, Helmut and Scheibel, Thomas R.}, title = {Biomineralization of engineered spider silk protein-based composite materials for bone tissue engineering}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-400519}, pages = {13}, year = {2017}, abstract = {Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering.}, language = {en} } @phdthesis{Peh2017, author = {Peh, Eddie K.W.}, title = {Calcium carbonate formation}, school = {Universit{\"a}t Potsdam}, pages = {133}, year = {2017}, language = {en} } @article{HentrichBrezesinskiKuebeletal.2017, author = {Hentrich, Doreen and Brezesinski, Gerald and Kuebel, Christian and Bruns, Michael and Taubert, Andreas}, title = {Cholesteryl Hemisuccinate Monolayers Efficiently Control Calcium Phosphate Nucleation and Growth}, series = {Crystal growth \& design : integrating the fields of crystal engineering and crystal growth for the synthesis and applications of new materials}, volume = {17}, journal = {Crystal growth \& design : integrating the fields of crystal engineering and crystal growth for the synthesis and applications of new materials}, publisher = {American Chemical Society}, address = {Washington}, issn = {1528-7483}, doi = {10.1021/acs.cgd.7b00753}, pages = {5764 -- 5774}, year = {2017}, abstract = {The article describes the phase behavior of cholesteryl hemisuccinate at the air-liquid interface and its effect on calcium phosphate (CP) mineralization. The amphiphile forms stable monolayers with phase transitions at the air-liquid interface from a gas to a tilted liquid-condensed (TLC) and finally to an untilted liquid-condensed (ULC) phase. CP mineralization beneath these monolayers leads to crumpled CP layers made from individual plates. The main crystal phase is octacalcium phosphate (OCP) along with a minor fraction of hydroxyapatite (HAP), as confirmed by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, bright field transmission electron microscopy, and electron diffraction.}, language = {en} } @article{PehLiedelTaubertetal.2017, author = {Peh, Eddie and Liedel, Clemens and Taubert, Andreas and Tauer, Klaus}, title = {Composition inversion to form calcium carbonate mixtures}, series = {CrystEngComm}, volume = {19}, journal = {CrystEngComm}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1466-8033}, doi = {10.1039/c7ce00433h}, pages = {3573 -- 3583}, year = {2017}, abstract = {Composition inversion takes place in equimolar solid mixtures of sodium or ammonium carbonate and calcium chloride with respect to the combination of anions and cations leading to the corresponding chloride and calcite in complete conversion. The transformation takes place spontaneously under a variety of different situations, even in a powdery mixture resting under ambient conditions. Powder X-ray diffraction data and scanning electron microscopy micrographs are presented to describe the course of the reaction and to characterize the reaction products. The incomplete reaction in the interspace between two compressed tablets of pure starting materials leads to an electric potential due to the presence of uncompensated charges.}, language = {en} } @article{ShainyanKirpichenkoKleinpeter2017, author = {Shainyan, Bagrat A. and Kirpichenko, Svetlana V. and Kleinpeter, Erich}, title = {Conformational Preferences of the Phenyl Group in 1-Phenyl-1-X-1-silacyclo-hexanes (X = MeO, HO) and 3-Phenyl-3-X-3-silatetrahydropyrans (X = HO, H) by Low Temperature C-13 NMR Spectroscopy and Theoretical Calculations}, series = {The journal of organic chemistry}, volume = {82}, journal = {The journal of organic chemistry}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.7b02505}, pages = {13414 -- 13422}, year = {2017}, abstract = {New Si-phenyl-substituted silacyclohexanes and 3-silatetrahydropyrans have been synthesized and studied with respect to the conformational equilibria of the heterosix-membered ring by low temperature C-13 NMR spectroscopy and quantum chemical calculations. For 1-methoxy-1-phenylsilacyclohexane 1 and 3-phenyl-3-silatetrahydropyran 4 the conformational equilibria could be frozen and assigned. The Ph-ax reversible arrow Ph-eq equilibrium constants at 103 K are 2.21 for 1 and 4.59 for 4. In complete agreement with former studies of similar silicon compounds, molecules 1 and 4 prefer to adopt the Pheq conformation. The conformational equilibria of 1-hydroxy-1-phenylsilacydohexane 2 and 3-hydroxy-3-phenyl-3-silatetrahydropyran 3 could not be frozen at 100 K and proved to be heavily one-sided (if not anancomeric). Obviously, there is a general trend of predominance of Phax conformer in the gas phase and of Pheq in solution. For the isolated molecules of silanols 2 and 3, calculations allowed to explain the axial predominance of the phenyl group by a larger polarization of the Si-Ph than of the Si-O bond in the Phax conformer and additional destabilization of 3-Ph-eq conformer by repulsion of unidirectional dipoles of the endocyclic oxygen lone pair and of the highly polar axial Si-O bond.}, language = {en} }