@article{WolffSchuelerGastetal.2020,
  author    = {Wolff, Martin and Sch{\"u}ler, Anja and Gast, Klaus and Seckler, Robert and Evers, Andreas and Pfeiffer-Marek, Stefania and Kurz, Michael and Nagel, Norbert and Haack, Torsten and Wagner, Michael and Thalhammer, Anja},
  title     = {Self-Assembly of Exendin-4-Derived Dual Peptide Agonists is Mediated by Acylation and Correlated to the Length of Conjugated Fatty Acyl Chains},
  series = {Molecular pharmaceutics},
  volume    = {17},
  journal   = {Molecular pharmaceutics},
  number    = {3},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1543-8384},
  doi       = {10.1021/acs.molpharmaceut.9b01195},
  pages     = {965 -- 978},
  year      = {2020},
  abstract  = {Dual glucagon-like peptide-1/glucagon receptor agonists have emerged as promising candidates for the treatment of diabetes and obesity. Issues of degradation sensitivity and rapid renal clearance are addressed, for example, by the conjugation of peptides to fatty acid chains, promoting reversible albumin binding. We use combined dynamic and static light scattering to directly measure the self-assembly of a set of dual peptide agonists based on the exendin-4 structure with varying fatty acid chain lengths in terms of apparent molecular mass and hydrodynamic radius (R-S). We use NMR spectroscopy to gain an insight into the molecular architecture of the assembly. We investigate conformational changes of the monomeric subunits resulting from peptide self-assembly and assembly stability as a function of the fatty acid chain length using circular dichroism and fluorescence spectroscopy. Our results demonstrate that self-assembly of the exendin-4-derived dual agonist peptides is essentially driven by hydrophobic interactions involving the conjugated acyl chains. The fatty acid chain length affects assembly equilibria and the assembly stability, although the peptide subunits in the assembly retain a dynamic secondary structure. The assembly architecture is characterized by juxtaposition of the fatty acyl side chains and a hydrophobic cluster of the peptide moiety. This cluster experiences local conformational changes in the assembly compared to the monomeric unit leading to a reduction in solvent exposure. The N-terminal half of the peptide and a C-terminal loop are not in contact with neighboring peptide subunits in the assemblies. Altogether, our study contributes to a thorough understanding of the association characteristics and the tendency toward self-assembly in response to lipidation. This is important not only to achieve the desired bioavailability but also with respect to the physical stability of peptide solutions.},
  language  = {en}
}
@article{WolffSchuelerGastetal.2020,
  author    = {Wolff, Martin and Sch{\"u}ler, Anja and Gast, Klaus and Seckler, Robert and Evers, Andreas and Pfeiffer-Marek, Stefania and Kurz, Michael and Nagel, Norbert and Haack, Torsten and Wagner, Michael and Thalhammer, Anja},
  title     = {Self-Assembly of Exendin-4-Derived Dual Peptide Agonists is Mediated by Acylation and Correlated to the Length of Conjugated Fatty Acyl Chains},
  series = {Molecular pharmaceutics},
  volume    = {17},
  journal   = {Molecular pharmaceutics},
  number    = {3},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {1543-8384},
  doi       = {10.1021/acs.molpharmaceut.9b01195},
  pages     = {965 -- 978},
  year      = {2020},
  abstract  = {Dual glucagon-like peptide-1/glucagon receptor agonists have emerged as promising candidates for the treatment of diabetes and obesity. Issues of degradation sensitivity and rapid renal clearance are addressed, for example, by the conjugation of peptides to fatty acid chains, promoting reversible albumin binding. We use combined dynamic and static light scattering to directly measure the self-assembly of a set of dual peptide agonists based on the exendin-4 structure with varying fatty acid chain lengths in terms of apparent molecular mass and hydrodynamic radius (R-S). We use NMR spectroscopy to gain an insight into the molecular architecture of the assembly. We investigate conformational changes of the monomeric subunits resulting from peptide self-assembly and assembly stability as a function of the fatty acid chain length using circular dichroism and fluorescence spectroscopy. Our results demonstrate that self-assembly of the exendin-4-derived dual agonist peptides is essentially driven by hydrophobic interactions involving the conjugated acyl chains. The fatty acid chain length affects assembly equilibria and the assembly stability, although the peptide subunits in the assembly retain a dynamic secondary structure. The assembly architecture is characterized by juxtaposition of the fatty acyl side chains and a hydrophobic cluster of the peptide moiety. This cluster experiences local conformational changes in the assembly compared to the monomeric unit leading to a reduction in solvent exposure. The N-terminal half of the peptide and a C-terminal loop are not in contact with neighboring peptide subunits in the assemblies. Altogether, our study contributes to a thorough understanding of the association characteristics and the tendency toward self-assembly in response to lipidation. This is important not only to achieve the desired bioavailability but also with respect to the physical stability of peptide solutions.},
  language  = {en}
}
@article{BaxaWeintraubSeckler2020,
  author    = {Baxa, Ulrich and Weintraub, Andrej and Seckler, Robert},
  title     = {Self-competitive inhibition of the bacteriophage P22 Tailspike endorhamnosidase by O-antigen oligosaccharides},
  series = {Biochemistry},
  volume    = {59},
  journal   = {Biochemistry},
  number    = {51},
  publisher = {American Chemical Society},
  address   = {Washington},
  issn      = {0006-2960},
  doi       = {10.1021/acs.biochem.0c00872},
  pages     = {4845 -- 4855},
  year      = {2020},
  abstract  = {The P22 tailspike endorhamnosidase confers the high specificity of bacteriophage P22 for some serogroups of Salmonella differing only slightly in their O-antigen polysaccharide. We used several biophysical methods to study the binding and hydrolysis of O-antigen fragments of different lengths by P22 tailspike protein. O-Antigen saccharides of defined length labeled with fluorophors could be purified with higher resolution than previously possible. Small amounts of naturally occurring variations of 0antigen fragments missing the nonreducing terminal galactose could be used to determine the contribution of this part to the free energy of binding to be similar to 7 kJ/mol. We were able to show via several independent lines of evidence that an unproductive binding mode is highly favored in binding over all other possible binding modes leading to hydrolysis. This is true even under circumstances under which the O-antigen fragment is long enough to be cleaved efficiently by the enzyme. The high-affinity unproductive binding mode results in a strong self-competitive inhibition in addition to product inhibition observed for this system. Self-competitive inhibition is observed for all substrates that have a free reducing end rhamnose. Naturally occurring O-antigen, while still attached to the bacterial outer membrane, does not have a free reducing end and therefore does not perform self-competitive inhibition.},
  language  = {en}
}