Isotopologues of a Metabolic Precursor for Selective N-15 and C-13 Histidine Labeling

  • J Mol Biol. 2025 Dec 1;437(23):169347. doi: 10.1016/j.jmb.2025.169347.
Sven Brüschweiler  1 ,  Matus Hlavac  1 ,  Sarah Kratzwald  2 ,  Julia Schörghuber  3 ,  Katharina M Siess  1 ,  Alisa Wimmer  2 ,  Gerald Platzer  1 ,  Robert Konrat  4 ,  Roman J Lichtenecker  5
Affiliations
  • 1. Mag-Lab, Karl-Farkas-Gasse 22, 1030 Vienna, Austria.
  • 2. Mag-Lab, Karl-Farkas-Gasse 22, 1030 Vienna, Austria; Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria.
  • 3. Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria.
  • 4. Department of Structural and Computational Biology, Max Perutz Laboratories, University of Vienna, Dr.-Bohr-Gasse 9, 1030 Vienna, Austria.
  • 5. Mag-Lab, Karl-Farkas-Gasse 22, 1030 Vienna, Austria; Institute of Organic Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 38, 1090 Vienna, Austria. Electronic address: [email protected].
PMID: 40669594 DOI: 10.1016/j.jmb.2025.169347
Abstract

Histidine is a versatile residue with distinct properties ensuring many proteins' structure and proper function. Its imidazole side-chain represents an ideal chemical entity to serve as a proton shuttle in enzyme mechanisms, control recognition interfaces either by contribution of its aromatic Pi system or in its cationic form, and acts as a coordinating ligand to metal cations. These functional capabilities are modulated by the local molecular environment, which influences pKa values and tautomeric states. NMR spectroscopy has proven to be a reliable method for probing the distinct functions of histidine. Here, we describe the synthesis of isotopically labeled variants of a non-chiral precursor to introduce NMR active 13C and/or 15N nuclei into histidine side-chains. The compounds were employed to selectively label protein targets of significant interest in current drug discovery programs, such as the WD repeat containing protein 5 (WDR5), the Src homology 2 domain of the Phospholipase C (PLCγ-SH2) and the product of the Kirsten rat sarcoma virus oncogene (KRAS).

Keywords
KRAS; WDR5; histidine; isotope labeling; protein NMR.
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