@article{TymoshenkoOnykiienkoMuelleretal.2017,
  author    = {Tymoshenko, Y. V. and Onykiienko, Y. A. and M{\"u}ller, T. and Thomale, R. and Rachel, S. and Cameron, A. S. and Portnichenko, P. Y. and Efremov, D. V. and Tsurkan, V. and Abernathy, D. L. and Ollivier, J. and Schneidewind, A. and Piovano, A. and Felea, V. and Loidl, A. and Inosov, D. S.},
  title     = {Pseudo-Goldstone magnons in the frustrated \(S=3/2\) Heisenberg helimagnet \(ZnCr_2Se_4\) with a pyrochlore magnetic sublattice},
  series = {Physical Review X},
  volume    = {7},
  journal   = {Physical Review X},
  number    = {4},
  doi       = {10.1103/PhysRevX.7.041049},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172770},
  year      = {2017},
  abstract  = {Low-energy spin excitations in any long-range ordered magnetic system in the absence of magnetocrystalline anisotropy are gapless Goldstone modes emanating from the ordering wave vectors. In helimagnets, these modes hybridize into the so-called helimagnon excitations. Here we employ neutron spectroscopy supported by theoretical calculations to investigate the magnetic excitation spectrum of the isotropic Heisenberg helimagnet \({ZnCr_2Se_4}\) with a cubic spinel structure, in which spin\(-3/2\) magnetic \({Cr^{3+}}\) ions are arranged in a geometrically frustrated pyrochlore sublattice. Apart from the conventional Goldstone mode emanating from the \((0~ 0~ {q_h})\) ordering vector, low-energy magnetic excitations in the single-domain proper-screw spiral phase show soft helimagnon modes with a small energy gap of \({∼0.17~ meV}\), emerging from two orthogonal wave vectors \(({q_h}~ 0~ 0)\) and \({(0~ {q_h}~ 0)}\) where no magnetic Bragg peaks are present. We term them pseudo-Goldstone magnons, as they appear gapless within linear spinwave theory and only acquire a finite gap due to higher-order quantum-fluctuation corrections. Our results are likely universal for a broad class of symmetric helimagnets, opening up a new way of studying weak magnon-magnon interactions with accessible spectroscopic methods.},
  language  = {en}
}
@article{MuellerSebaldOschkinat1994,
  author    = {M{\"u}ller, T. and Sebald, Walter and Oschkinat, H.},
  title     = {Antagonist design through forced electrostatic mismatch},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62408},
  year      = {1994},
  abstract  = {No abstract available},
  subject      = {Biochemie},
  language  = {en}
}
@article{MuellerDieckmannSebaldetal.1994,
  author    = {M{\"u}ller, T. and Dieckmann, T. and Sebald, Walter and Oschkinat, H.},
  title     = {Aspects of receptor binding and signalling of interleukin-4 investigated by site-directed mutagenesis and NMR spectroscopy},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62444},
  year      = {1994},
  abstract  = {Cytokines are hormones that carry information from ceJI to ceH. This information is read from their surface upon binding to transmembrane receptors and by the subsequent initiation of receptor oligomerization. An inftuence on this process through mutagenesis on the hormone surface is highly desirab)e for medical reasons. However, an understanding of hormone-receptor interactions requires insight into the structural changes introduced by the mutations. In this line structural studies on human TL-4 and the medically important IL-4 antagonists YI24D and Y124G are presented. The site a.round YI24 is an important epitope responsible for the a.bility of 11-4 t.o ca.use a signal in the target cells. It is shown that the local main-chain structure around residue 124 in the variants remains unchanged. A strategy is presented here which allows the study of these types of proteins and their variants by NMR which does not require carbon Iabeiied sa.mples.},
  subject      = {Biochemie},
  language  = {en}
}
@article{KruseShenArnoldetal.1993,
  author    = {Kruse, N. and Shen, B. J. and Arnold, S. and Tony, H. P. and M{\"u}ller, T. and Sebald, Walter},
  title     = {Two distinct functional sites of human interleukin 4 are identified by variants impaired in either receptor binding or receptor activation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-62451},
  year      = {1993},
  abstract  = {Interleukin 4 (IL-4) exerts a decisive role in the coord.ination of proteelive immune responses against parasites, particularly helminths. A disregulation of ll.r4 function is possibly involved in the genesis of allergic disease states. The search for important amino acid residues in human ll.r4 by mutational analysis of charged invariant amino acid positions identified two distinct functional sites in the 4-helix-bundle protein. Site 1 was marked by amino acid substitutions of the glutamic acid at position 9 in helix A and arginine at position 88 in helix C. Exchanges at both positions led to IL-4 variants deficient in binding to the extracellular domain of the ll.r4 receptor (IL-4ReJ. In parallel, up to 1000-fold increased concentrations of this type of variant were required to induce T -cell proliferation and B-eeil CD23 expression. Site 2 was marked by amino acid exchanges in helix D at positions 121, 124 and 125 (arginine, tyrosine and serine respectively in the wild-type).ß.A variants affected at site 2 exhibited partial agonist activity during T -cell proliferation; however, they still bound with high affinity to IL-4Rex. [The generation of an IL-4 antagonist by replacing tyrosine 124 with aspartic acid has been described before by Kruse et al. (1992) (EMBO }., 11, 3237-3244)]. These findings indicate that IL-4 functions by bind.ing IL-4Rex via site 1 which is constituted by residues on helices A and C. They further suggest that the association of a second, still undetined receptor protein with site 2 in helix D activates the receptor system and generates a transmembrane signal.},
  subject      = {Biochemie},
  language  = {en}
}