Quinones are essential cofactors in many physiological processes, among them proton-coupled electron transfer (PCET) in photosynthesis and respiration. A key intermediate in PCET is the ...monoprotonated semiquinone radical. In this work we produced the monoprotonated benzosemiquinone (BQH•) by UV illumination of BQ dissolved in 2-propanol at cryogenic temperatures and investigated the electronic and geometric structures of BQH• in the solid state (80 K) using EPR and ENDOR techniques at 34 GHz. The g-tensor of BQH• was found to be similar to that of the anionic semiquinone species (BQ•–) in frozen solution. The peaks present in the ENDOR spectrum of BQH• were identified and assigned by 1H/2H substitutions. The experiments reconfirmed that the hydroxyl proton (O–H) on BQH•, which is abstracted from a solvent molecule, mainly originates from the central CH group of 2-propanol. They also showed that the protonation has a strong impact on the electron spin distribution over the quinone. This is reflected in the hyperfine couplings (hfc’s) of the ring protons, which dramatically changed with respect to those typically observed for BQ•–. The hfc tensor of the O–H proton was determined by a detailed orientation-selection ENDOR study and found to be rhombic, resembling those of protons covalently bound to carbon atoms in a π-system (i.e., α-protons). It was found that the O–H bond lies in the quinone plane and is oriented along the direction of the quinone oxygen lone pair orbital. DFT calculations were performed on different structures of BQH• coordinated by four, three, or zero 2-propanol molecules. The O–H bond length was found to be around 1.0 Å, typical for a single covalent O–H bond. Good agreement between experimental and DFT results were found. This study provides a detailed picture of the electronic and geometric structures of BQH• and should be applicable to other naturally occurring quinones.
Motivic Springer theory Eberhardt, Jens Niklas; Stroppel, Catharina
Indagationes mathematicae,
January 2022, 2022-01-00, Volume:
33, Issue:
1
Journal Article
Peer reviewed
Open access
We show that representations of convolution algebras such as Lustzig’s graded affine Hecke algebra or the quiver Hecke algebra and quiver Schur algebra in type A and A˜ can be realized in terms of ...certain equivariant motivic sheaves called Springer motives. To this end, we lay foundations to a motivic Springer theory and prove formality results using weight structures.
As byproduct, we express Koszul and Ringel duality in terms of a weight complex functor and show that partial quiver flag varieties in type A˜ (with cyclic orientation) admit an affine paving.
The triplet state of the carotenoid peridinin in the refolded N-domain peridinin-chlorophyll-protein (PCP) antenna complex from Amphidinium carterae is investigated by orientation-selected pulse ...Q-band ENDOR spectroscopy (34 GHz). The peridinin triplet is created by triplet−triplet transfer from 3Chl a, generated by illumination at 630 nm. The peridinin triplet lifetimes are close to the minimum duration of the pulse ENDOR experiment (∼10 μs). Thirteen proton hyperfine coupling (hfc) tensors are deduced for the peridinin triplet state. Additionally, density functional theory (DFT) calculations are presented which aided in the assignment of proton hfcs. The number and magnitude of the resolved hfcs indicate that only one specific peridinin in PCP carries the triplet exciton. The experiments enable us to derive for the first time information about the wavefunction of the triplet electrons (S = 1) in a carotenoid molecule, which is a sensitive probe for the electronic and geometric structure of this short-lived excited state in the protein matrix.
We prove a monoidal equivalence, called universal Koszul duality, between genuine equivariant K-motives on a Kac-Moody flag variety and constructible monodromic sheaves on its Langlands dual. The ...equivalence is obtained by a Soergel-theoretic description of both sides which extends results for finite-dimensional flag varieties by Taylor and the first author. Universal Koszul duality bundles together a whole family of equivalences for each point of a maximal torus. At the identity, it recovers an ungraded version of Beilinson-Ginzburg-Soergel's and Bezrukavnikov-Yun's Koszul duality for equivariant and unipotently monodromic sheaves. It also generalizes Soergel-theoretic descriptions for monodromic categories on finite-dimensional flag varieties by Lusztig-Yun, Gouttard and the second author. For affine Kac-Moody groups, our work sheds new light on the conjectured quantum Satake equivalences by Cautis-Kamnitzer and Gaitsgory. On our way, we establish foundations on six functors for reduced K-motives and introduce a formalism of constructible monodromic sheaves.
We define a filtration of a standard Whittaker module over a complex semisimple Lie algebra and and establish its fundamental properties. Our filtration specialises to the Jantzen filtration of a ...Verma module for a certain choice of parameter. We prove that embeddings of standard Whittaker modules are strict with respect to our filtration, and that the filtration layers are semisimple. This provides a generalisation of the Jantzen conjectures to Whittaker modules. We prove these statements in two ways. First, we give an algebraic proof which compares Whittaker modules to Verma modules using a functor introduced by Backelin. Second, we give a geometric proof using mixed twistor \(\mathcal{D}\)-modules.
For a real affine hyperplane arrangement, we define an integer intersection matrix with a natural \(q\)-deformation related to the intersections of bounded chambers of the arrangement. By connecting ...the integer matrix to a bilinear form of Schechtman-Varchenko, we show that there is a closed formula for its determinant that only depends on the combinatorics of the underlying matroid. We conjecture an analogous formula for its \(q\)-deformation. Our work also applies more generally in the setting of affine oriented matroids. Additionally, we give a representation-theoretic interpretation of our \(q\)-intersection matrix using Braden-Licata-Proudfoot-Websters's hypertoric category \(\mathcal{O}\) (or more generally Kowalenko-Mautner's category \(\mathcal{O}\) for oriented matroid programs). This paper is part of a broader program to categorify matroidal Schur algebras defined by Braden-Mautner.
Quantum low-density parity-check (qLDPC) codes offer a promising route to scalable fault-tolerant quantum computation with constant overhead. Recent advancements have shown that qLDPC codes can ...outperform the quantum memory capability of surface codes even with near-term hardware. The question of how to implement logical gates fault-tolerantly for these codes is still open. We present new examples of high-rate bivariate bicycle (BB) codes with enhanced symmetry properties. These codes feature explicit nice bases of logical operators (similar to toric codes) and support fold-transversal Clifford gates without overhead. As examples, we construct \(98,6,12\) and \(162, 8, 12\) BB codes which admit interesting fault-tolerant Clifford gates. Our work also lays the mathematical foundations for explicit bases of logical operators and fold-transversal gates in quantum two-block and group algebra codes, which might be of independent interest.
We initiate the study of K-theory Soergel bimodules-a K-theory analog of classical Soergel bimodules. Classical Soergel bimodules can be seen as a completed and infinitesimal version of their new ...K-theoretic analog. We show that morphisms of K-theory Soergel bimodules can be described geometrically in terms of equivariant K-theoretic correspondences between Bott-Samelson varieties. We thereby obtain a natural categorification of K-theory Soergel bimodules in terms of equivariant coherent sheaves. We introduce a formalism of stratified equivariant K-motives on varieties with an affine stratification, which is a K-theoretric analog of the equivariant derived category of Bernstein-Lunts. We show that Bruhat-stratified torus-equivariant K-motives on flag varieties can be described in terms of chain complexes of K-theory Soergel bimodules. Moreover, we propose conjectures regarding an equivariant/monodromic Koszul duality for flag varieties and the quantum K-theoretic Satake.
Metabolic flux analysis in eukaryotes Niklas, Jens; Schneider, Konstantin; Heinzle, Elmar
Current opinion in biotechnology,
02/2010, Volume:
21, Issue:
1
Journal Article
Peer reviewed
Metabolic flux analysis (MFA) represents a powerful tool for systems biology research on eukaryotic cells. This review describes recent advances, the challenges as well as applications of metabolic ...flux analysis comprising fungi, mammalian cells and plants. While MFA is widely established and applied in microorganisms, it remains still a challenge to adapt these methods to eukaryotic cell systems having a higher complexity particularly concerning compartmentation or media composition. In fungi MFA was used in the past few years to analyze a variety of conditions and factors and their effects on cellular metabolism. In mammalian cells MFA was applied mainly in cell culture technology and in medical and toxicological research.13 C metabolic studies on native whole plants are additionally challenging by the fact that CO2 is usually the only carbon source.
We construct an ungraded version of Beilinson-Ginzburg-Soergel's Koszul duality for Langlands dual flag varieties, inspired by Beilinson's construction of rational motivic cohomology in terms of ...\(K\)-theory. For this, we introduce and study categories \(\operatorname{DK}_{\mathcal{S}}(X)\) of \(\mathcal{S}\)-constructible \(K\)-motivic sheaves on varieties \(X\) with an affine stratification \(\mathcal{S}\). We show that there is a natural and geometric functor, called Beilinson realisation, from \(\mathcal{S}\)-constructible mixed sheaves \(\operatorname{D}^{mix}_{\mathcal{S}}(X)\) to \(\operatorname{DK}_{\mathcal{S}}(X)\). We then show that Koszul duality intertwines the Betti realisation and Beilinson realisation functors and descends to an equivalence of constructible sheaves and constructible \(K\)-motivic sheaves on Langlands dual flag varieties.
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