Eldorado - Repositorium der TU Dortmund

Ressourcen aus und für Forschung, Lehre und Studium

Bei diesem Service handelt es sich um das Institutionelle Repositorium der Technischen Universität Dortmund. Hier werden Ressourcen aus und für Lehre, Studium und Forschung gespeichert, erschlossen und der Öffentlichkeit zugänglich gemacht.

Hauptbereiche in Eldorado

Wählen Sie einen Bereich, um dessen Inhalt anzusehen.

Gerade angezeigt 1 - 5 von 9

Fach- und Universitätsübergreifendes 1319
Fakultäten 13954
Graduate School und Graduiertenkollegs 12
Hochschulverwaltung 1251
Sonderforschungsbereiche 1595

Aktuellste Veröffentlichungen

On a lack of stability of parametrized BV solutions to rate‐independent systems with nonconvex energies and discontinuous loads
(Wiley, 2024-04-26) Andreia, Merlin; Meyer, Christian
We consider a rate-independent system with nonconvex energy under discontinuous external loading. The underlying space is finite-dimensional and the loads are functions in 𝐵⁢𝑉⁡([0,𝑇];ℝ𝑑). We investigate the stability of various solution concepts w.r.t. a sequence of loads converging weakly* in 𝐵⁢𝑉⁡([0,𝑇];ℝ𝑑) with a particular emphasis on the so-called normalized, 𝔭-parametrized balanced viscosity solutions. By means of three counterexamples, it is shown that common solution concepts are not stable w.r.t. weak* and even intermediate (or strict) convergence of loads in the sense that a limit of a sequence of solutions associated with these loads need not be a solution corresponding to the load in the limit. We moreover introduce a new solution concept, which is stable in this sense, but our examples show that this concept necessarily allows “solutions” that are physically meaningless.
N‐Cyanopiperazines as specific covalent inhibitors of the deubiquitinating enzyme UCHL1
(Wiley, 2024-01-19) Schmidt, Mirko; Grethe, Christian; Recknagel, Sarah; Kipka, Gian‐Marvin; Klink, Nikolas; Gersch, Malte
Cyanamides have emerged as privileged scaffolds in covalent inhibitors of deubiquitinating enzymes (DUBs). However, many compounds with a cyanopyrrolidine warhead show cross-reactivity toward small subsets of DUBs or toward the protein deglycase PARK7/DJ-1, hampering their use for the selective perturbation of a single DUB in living cells. Here, we disclose N’-alkyl,N-cyanopiperazines as structures for covalent enzyme inhibition with exceptional specificity for the DUB UCHL1 among 55 human deubiquitinases and with effective target engagement in cells. Notably, transitioning from 5-membered pyrrolidines to 6-membered heterocycles eliminated PARK7 binding and introduced context-dependent reversibility of the isothiourea linkage to the catalytic cysteine of UCHL1. Compound potency and specificity were analysed by a range of biochemical assays and with a crystal structure of a cyanopiperazine in covalent complex with UCHL1. The structure revealed a compound-induced conformational restriction of the cross-over loop, which underlies the observed inhibitory potencies. Through the rationalization of specificities of different cyanamides, we introduce a framework for the investigation of protein reactivity of bioactive nitriles of this compound class. Our results represent an encouraging case study for the refining of electrophilic compounds into chemical probes, emphasizing the potential to engineer specificity through subtle chemical modifications around the warhead.
Non‐templated assembly of D5h‐symmetric Pd5L10 rings by precise ligand angle adjustment
(Wiley, 2024-03-05) Neukirch, Laura; Kulas, Milan D.; Holstein, Julian J.; Clever, Guido H.
We report a series of Pd(II)nL2n coordination rings for which nuclearity is controlled by the binding angle of the corresponding bis-monodentate bridging ligands. Judicious choice of the angle within a family of rather rigid ligands allowed for the first-time to synthesize a homoleptic five-membered Pd5L10 ring that does not require any template to form. We demonstrate that control over the ring size is maintained both in the solid-, solution-, and gas-phase. Two X-ray structures of five-membered rings from ligands with ideal angles (yielding a perfect pentagonal ring) vs. suboptimal angles (resulting in a highly distorted structure) illustrate the importance of the correct ligand geometry. A mathematical model for estimating the expected ring size based on the ligand angle was derived and DFT computations show that ring-strain is the major factor determining the assembly outcome.
On the suitability of the α‐relaxation as novel trigger for a shape memory polymer
(Wiley, 2024-09-07) Maricanov, Michail; Becker, Roman; Jerusalem, Robert David Ludwig; Tiller, Joerg Christian; Katzenberg, Frank
Shape memory polymers typically utilize the glass transition or melting temperature to switch from one shape to another. The goal of this work is to check if the α-relaxation, which is attributed to the migration of chains through lamellar crystals, can be utilized as novel switch for any crosslinkable semi-crystalline thermoplastic. Using cross-linked low-density polyethylene (x-LDPE) as an example, it is shown that the α-relaxation is indeed suitable as switch, when the polymer is crystallized under strain to an intermediate shape. It is demonstrated that post-stretching at a temperature between the α-relaxation and the melting temperature, followed by subsequent cooling to room-temperature switches x-LDPE from the intermediate to a temporary shape and that reheating to this temperature initiates the retraction back to the intermediate shape. Switching between intermediate and temporary shapes is shown to be accompanied by a reversible change in morphology.
Phenazinium‐ and malachite green‐based Pd(II) cages: chiroptical discrimination of nucleoside triphosphates
(Wiley, 2024-10-29) Durmisevic, Armin; Regeni, Irene; Namoro, Mark Ely; Baksi, Ananya; Clever, Guido H.
Organic chromophores have been successfully implemented into supramolecular systems to bestow them with distinct photophysical properties for various applications, ranging from solar energy conversion, photochemical reactions or as receptors for guest molecules with optical readout. We had previously introduced first members of the large family of coal-tar dyes (methylene blue, crystal violet and rhodamine) as integral components of coordination cages. Here, we add two new chromophores, malachite green (MGP) and a purple phenazinium dye (PHP), serving as backbones of bis-monodentate banana-shaped ligands with pyridine donors. We show the formation of corresponding green and purple coloured Pd2L4 coordination cages and investigate their interaction with chiral guest molecules via UV-Vis and CD spectroscopy. The PHP cage can be used to recognize nucleoside triphosphates, based on chirality transfer from the guests to the structurally flexible helicate. In combination with the already known methylene blue cage MBP we could further differentiate between all four canonical NTPs through characteristic changes in the observed CD signatures.