Inhibition of peptide aggregation by means of enzymatic phosphorylation

• Kristin Folmert,
• Malgorzata Broncel,
• Hans v. Berlepsch,
• Christopher H. Ullrich,
• Mary-Ann Siegert and
• Beate Koksch

Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240

• protofilaments and on to insoluble amyloid fibrils, and we found a remarkable directing effect from β-sheet-rich structures to unfolded structures in the initial growth phase, in which small oligomers and protofilaments prevail if the peptide is phosphorylated. Keywords: aggregation; amyloids; peptide models

• the subject of numerous studies, the pathway of aggregation from soluble α-helical-rich or partially unfolded peptides into insoluble β-sheet-rich amyloid fibrils remains unclear. Several studies discovered parameters of peptide environment, like pH [12][13], oxidative stress [14], presence of organic

• characteristics, outstanding stability, regular fibrous architecture and high synthetic accessibility with numerous chemoselective ligation and modification methods [24][25][26]. Also, various post-translational modifications, like phosphorylation or glycosylation have been studied as aggregation triggers [27][28

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

• Pierre Boufflet,
• Sebastian Wood,
• Jessica Wade,
• Zhuping Fei,
• Ji-Seon Kim and
• Martin Heeney

Beilstein J. Org. Chem. 2016, 12, 2150–2163, doi:10.3762/bjoc.12.205

• block copolymer case, non-fluorinated segments appear to slightly frustrate the aggregation of the more fluorinated block. However, in situ temperature dependent Raman spectroscopy shows that the intramolecular order is more thermally stable in the block copolymer than in the corresponding blend

• interpretation of the vibronic structure in relation to the order in the thin film, it is worth noting that the vibronic structure of the block copolymers in both cases is less pronounced than for the corresponding blend. Considering the aformentioned link between the vibronic structure and aggregation, this

• melting and crystallization temperatures, an effect that was predominantly attributed to the increased backbone planarity and rigidity in combination with the increased aggregation it engenders [42]. In order to probe the crystallization behavior of the block copolymers and blends in thin films, DSC was

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• S4). In addition this behavior underlines that no aggregation of the molecules has to be taken into account at the concentration level of absorption and emission spectroscopy. In the UV–vis spectra, most characteristically, four absorption bands are found, three at shorter wavelengths arising from

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• still shows some large aggregates in blend films [10]. The addition of pyrrolic phenylacetylene substituents further helped to break the aggregation and to create a favorable nanoscale phase separation in blend films, leading to higher PCEs [9][10]. DFT calculations show that Zn(WS3)2 is a very large

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• majority of applications of microflow setups involved reagents in the same aggregation state (homogeneous, mostly liquid phase). In contrast, an especially complex problem beyond the scope of most microreactor setups are heterogeneous reactions [31][32] between three dispersed entities such as a liquid

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

• Vincent M. Rotello

Beilstein J. Org. Chem. 2016, 12, 1638–1646, doi:10.3762/bjoc.12.161

• aggregation became an issue when we attempted to sense changes in serum profiles. We overcame this issue using Nature's fluorescent polymers, namely fluorescent proteins. Using gold nanoparticles and green fluorescent protein we were able to rapidly detect very small changes in serum protein profiles in

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• optical characterization, both in solution and thin-film, indicated that PTzBDT-1 has a red-shifted optical absorption compared to PTzBDT-2, likely due to a more planar conformation of the polymer backbone promoted by the lower content of alkyl side chains. The different aggregation in the solid state

• performance is presumably attributed to the limited solubility of the PTzBDT-1 in organic solvents resulting in enhanced aggregation and poor intermixing with the acceptor material in the active layer. Keywords: alkyl side chains; benzodithiophene; bulk heterojunction solar cells; 2D conjugated polymers

• aggregation, in solution and solid state, of the polymer chains. The solution absorption spectra of the polymers (Figure 1A) exhibit an evident red-shift (~20 nm) of the λmax of PTzBDT-1 compared to PTzBDT-2 (550/598 nm and 530/574 nm, respectively). Moreover, PTzBDT-1 shows a broader spectrum in comparison

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• consistent with the increment in the oscillator strength revealed by the DFT calculation results. The ICT absorption peaks are slightly red-shifted and broadened in the solid thin films as compared to those in the chloroform solutions, which can be ascribed to molecular aggregation in the condensed solid

Artificial Diels–Alderase based on the transmembrane protein FhuA

• Hassan Osseili,
• Daniel F. Sauer,
• Klaus Beckerle,
• Marcus Arlt,
• Tomoki Himiyama,
• Tino Polen,
• Akira Onoda,
• Ulrich Schwaneberg,
• Takashi Hayashi and
• Jun Okuda

Beilstein J. Org. Chem. 2016, 12, 1314–1321, doi:10.3762/bjoc.12.124

• oxidized to Cu(II) by contamination with air. Cu(II) led to protein aggregation and precipitation. This was shown in an independent experiment. When one equiv of Cu(NO3)2·3H2O was added to a solution of FhuA ΔCVFtev, the protein precipitated rapidly and quantitatively. MALDI–TOF–MS analysis for the whole

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• sector in generating structure and function diverse O-nitrate esters for use as in vivo NO-donors. In this context particular emphasis has been placed on developing O-nitrate esters as biologically active agents that act on acetylcholinesterase (AChE), amyloid-βx-42 (Aβ42) aggregation, cyclooxygenase-II

Stimuli-responsive HBPS-g-PDMAEMA and its application as nanocarrier in loading hydrophobic molecules

• Yongsheng Chen,
• Li Wang,
• Haojie Yu,
• Zain-Ul-Abdin,
• Ruoli Sun,
• Guanghui Jing,
• Rongbai Tong and
• Zheng Deng

Beilstein J. Org. Chem. 2016, 12, 939–949, doi:10.3762/bjoc.12.92

• aggregation behavior of HBPS-g-PDMAEMA The electrostatic interaction is a major factor to influence the behavior of PDMAEMA in aqueous solution. So in this work, the influence of ionic strength, which affects the electrostatic interactions, was studied. In this case, pH was not adjusted and deionized water

• aqueous solution with relatively low concentrations of NaCl, and there was no maximum point. This is because higher concentrations of NaCl lowered the repulsive electrostatic interactions between PDMAEMA chains. So, higher concentrations of NaCl led to smaller aggregation sizes. The change of size was

• electrostatic interaction of PDMAEMA segments, so aggregation occurred and large sized aggregates were formed. Effect of the pH value on the phase-transition of HBPS-g-PDMAEMA The phase-inversion behavior of HBPS-g-PDMAEMA depends on the hydrophobicity of PDMAEMA chains. The protonation of the tethered amine

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• aggregation in this solvent, as for example reported for 9-(4-dimethylaminophenyl)benzo[b]quinolizinium in aqueous solution [14]. Though, exemplary control experiments with derivative 6c showed that the absorption of this compound depends linearly on the concentration (cf. Supporting Information File 1

• ), which contradicts aggregation. Furthermore, the absorption band of 6c is essentially maintained with increasing concentration. This behavior also indicates the absence of aggregates as the latter are characterized by the formation of red- or blue-shifted absorption bands or shoulders [35][36]. The

New synthetic strategies for xanthene-dye-appended cyclodextrins

• Milo Malanga,
• Andras Darcsi,
• Mihaly Balint,
• Gabor Benkovics,
• Tamas Sohajda and
• Szabolcs Beni

Beilstein J. Org. Chem. 2016, 12, 537–548, doi:10.3762/bjoc.12.53

• made from the frequencies of all the compounds composing the mixture. An incomplete fluorescent tagging of the starting single-isomer β-CD (and/or inadequate purification), as well as aggregation of the compound, can cause broadening of the peaks [23]. In the proton spectrum in Figure 4, the good

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• . The aggregation of these units creates a hydrophobic environment in which the two aromatic aldehydes are subjected to catalysis (Scheme 4) [12]. Asymmetric homo-benzoin reactions Much of the progress in the area of NHC-catalysed asymmetric benzoin reactions has been covered in two excellent reviews [6

Diastereoselective synthesis of new O-alkylated and C-branched inositols and their corresponding fluoro analogues

• Charlotte Collet,
• Françoise Chrétien,
• Yves Chapleur and
• Sandrine Lamandé-Langle

Beilstein J. Org. Chem. 2016, 12, 353–361, doi:10.3762/bjoc.12.39

• protein (Aβ), characteristic aggregation in Alzheimer disease (AD), and more specifically Aβ42 peptide allowing its conformational change and its stabilization into small, nonfibrillar complexes, less toxic for neuronal cells [20][21][22][23]. The most efficient representative, scyllo-inositol, was shown

• the corresponding fluoroinositol (1-fluoro-1-deoxy-scyllo-inositol) was also a good candidate to limit this aggregation. However, in vivo studies in animal models of Alzheimer disease with 1-[18F]fluoro-1-deoxy-scyllo-inositol used as radiotracer for positron emission tomography (PET) have shown that

Enabling technologies and green processes in cyclodextrin chemistry

• Giancarlo Cravotto,
• Marina Caporaso,
• Laszlo Jicsinszky and
• Katia Martina

Beilstein J. Org. Chem. 2016, 12, 278–294, doi:10.3762/bjoc.12.30

• preparation of CD thiols and thioethers is an emerging challenge because of the importance of intermediary azido derivatives [96] and favorable aggregation properties in nanomedicines and particularly the antidote Sugammadex [97]. The reaction between 6I-O-monotosyl-β-CD and various nucleophiles opens a new

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• emerged was a beautiful story [3][4][5] (and method) that is still being used to determine the aggregation state of lithium enolates [6][7][8][9] and alkoxides [10][11][12][13]. From Dave, I learned a tremendous amount about being a scientist. One of the most important take-home messages was that all data

• structures, such as ribbons, fibers, and sheets. This self-aggregation is driven by noncovalent interactions, including hydrogen bonding, π stacking, van der Waals interactions, and halogen bonding. Physical interactions amongst these larger structures lead to gel formation. Because noncovalent interactions

Supramolecular structures based on regioisomers of cinnamyl-α-cyclodextrins – new media for capillary separation techniques

• Gabor Benkovics,
• Ondrej Hodek,
• Martina Havlikova,
• Zuzana Bosakova,
• Pavel Coufal,
• Milo Malanga,
• Eva Fenyvesi,
• Andras Darcsi,
• Szabolcs Beni and
• Jindrich Jindrich

Beilstein J. Org. Chem. 2016, 12, 97–109, doi:10.3762/bjoc.12.11

• homosupramolecular interactions between the same species were missing. This work clearly demonstrates that the intermolecular complex formation is a regioselective process where the CD cavity can differentiate between the positional isomers which will result in different aggregation behavior of the regioisomers

• prepare the two regioisomers of Cin-α-CD in gram-scale which was required for the detailed characterization of their aggregation ability and for their application in capillary electrophoresis (CE). The monosubstituted products were characterized by ESI mass spectrometry, 1H NMR and 13C NMR spectroscopy

• aggregation was observed for both derivatives (see Record 3 in Figure 7 and Figure 8). Those were present in molecularly dispersed form with a Dh around 1.25 nm, which corresponds to the size of the unmodified, non-aggregated α-CD [14]. These results are in agreement with the results obtained by NMR

Aggregation behavior of amphiphilic cyclodextrins in a nonpolar solvent: evidence of large-scale structures by atomistic molecular dynamics simulations and solution studies

• Giuseppina Raffaini,
• Fabio Ganazzoli and
• Antonino Mazzaglia

Beilstein J. Org. Chem. 2016, 12, 73–80, doi:10.3762/bjoc.12.8

• nanoaggregates even in apolar solvents. Keywords: aggregation; amphiphilic cyclodextrins; molecular dynamics; nanoparticles; self-assembly; simulations; Introduction Amphiphilic cyclodextrins (aCD) are a class of molecules highly investigated for their self-assembly properties and inherent potential

• molecular recognition [3] or nanocarriers for drug delivery [4]. In the recent past, the aggregation behavior of aCD was investigated in water, getting insights on the structures of free nanoassemblies [5][6] or in combination with therapeutic agents [7]. However, in some stages of preparation and

• of the initial aggregation stage could easily take place. In particular, these simulations carried out with relatively small systems comprising a few molecules allowed us to assess that the driving force for aggregation was due to a synergy of different contributions. In particular, we found that the

Supramolecular polymer assembly in aqueous solution arising from cyclodextrin host–guest complexation

• Jie Wang,
• Zhiqiang Qiu,
• Yiming Wang,
• Li Li,
• Xuhong Guo,
• Duc-Truc Pham,
• Stephen F. Lincoln and
• Robert K. Prud’homme

Beilstein J. Org. Chem. 2016, 12, 50–72, doi:10.3762/bjoc.12.7

• carboxylate on average. This was attributed to aggregation of the dimers as a consequence of their amphiphilic nature, complexation of the octamethylene linker in the β-CD dimer annuli, and hydrogen bonding interactions between their β-CD annuli. The 1:1 complexation constants, 10−4K11 = 7.96, 2.32 and 26.42

• found that the adamantyl substituents aggregate in aqueous solution to form a micelle and that subsequent addition of α-CD leads to the formation of a supramolecular hydrogel as shown in Figure 11 [88]. The driving force for gelation is a combination of the hydrophobic aggregation of the adamantyl

• substituents and the aggregation of the α-CD complexed portions of the AD-PEG chains. Part of the interest in these low molecular weight polymer systems arises because they are able to pass through the kidney membrane [89] and are consequently of interest as components of drug-delivery systems [89][90]. A

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• phase solubility profiles are generally apparent values that combine several effects on the guest solubility: inclusion complexation, self-association of poorly soluble guests, self-aggregation of CD:guest complexes, as well as non-inclusion interaction and micelles formation [38]. The solubilizing

Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time ¹³C CP-MAS solid-state NMR characterization

• Isabelle Mallard,
• Davy Baudelet,
• Franca Castiglione,
• Monica Ferro,
• Walter Panzeri,
• Enzio Ragg and
• Andrea Mele

Beilstein J. Org. Chem. 2015, 11, 2785–2794, doi:10.3762/bjoc.11.299

• absence of light diffraction, as expected in the case of toluene aggregation, was controlled by recording the UV–vis absorption spectra in the visible region (400–700 nm), outside the absorption range of toluene. As flattened signals with absorbances close to zero were obtained for all of the mixtures

Enantioselective additions of copper acetylides to cyclic iminium and oxocarbenium ions

• Jixin Liu,
• Srimoyee Dasgupta and
• Mary P. Watson

Beilstein J. Org. Chem. 2015, 11, 2696–2706, doi:10.3762/bjoc.11.290

• , indicting that catalyst aggregation occurs under these reaction conditions [58]. It is unclear at this point, whether these catalyst aggregates are on or off the catalytic cycle. Conclusion As described above, highly enantioselective, copper-catalyzed alkynylations of cyclic iminium and oxocarbenium ion

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• results [50]. Interestingly, 3·TM-γCD shows a much stronger 0–1 transition than the 0–0 one, as the non-rotaxane copolymer 3, which might be indicative of some aggregation even though we do not observe a strong tail in the 500–600 nm regions (apart from the minor red-shift mentioned earlier). We also note

Assembly of synthetic Aβ miniamyloids on polyol templates

• Sebastian Nils Fischer and
• Armin Geyer

Beilstein J. Org. Chem. 2015, 11, 2646–2653, doi:10.3762/bjoc.11.284

• the first step of Aβ oligomerization. In the present article, we further develop the idea of systematic variation of the oligomerization degree of Aβ fragments by using dynamic covalent chemistry for the assembly of miniamyloids. The size of a polyol template will limit the aggregation degree of Aβ

• chemistry is the self-correcting reversibility if individual peptides which are bound in the wrong orientation resulting in a strong preference for defined ring sizes [18] or oligomerization degrees [19]. The idea appears especially attractive for the assembly of peptides with high aggregation tendencies

• reversible dynamic chemistry of specific oligomers are suitable for oligopeptides. Disulfide bonds seem to be the natural choice for the reversible covalent chemistry of peptides, but it appeared to us impossible to prevent both the template and the peptide from homo-oligomer formation. Self-aggregation is