2. Academic Validation
  3. Antivitamin B12 Inhibition of the Human B12 -Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate

Antivitamin B12 Inhibition of the Human B12 -Processing Enzyme CblC: Crystal Structure of an Inactive Ternary Complex with Glutathione as the Cosubstrate

  • Angew Chem Int Ed Engl. 2017 Jun 19;56(26):7387-7392. doi: 10.1002/anie.201701583.
Markus Ruetz 1 2,  Aranganathan Shanmuganathan 3,  Carmen Gherasim 2 4,  Agnes Karasik 3,  Robert Salchner 1 5,  Christoph Kieninger 1,  Klaus Wurst 6,  Ruma Banerjee 2,  Markos Koutmos 3,  Bernhard Kräutler 1
Affiliations

Affiliations

  • 1 Institute of Organic Chemistry and Center for Molecular Biosciences, University of Innsbruck, 6020, Innsbruck, Austria.
  • 2 University of Michigan Medical School, Ann Arbor, USA.
  • 3 Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, USA.
  • 4 Current address: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA.
  • 5 Current address: Watercryst GmbH & Co, Kematen, Austria.
  • 6 Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Austria.
PMID: 28544088 DOI: 10.1002/anie.201701583
Abstract

B12 antivitamins are important and robust tools for investigating the biological roles of vitamin B12 . Here, the potential antivitamin B12 2,4-difluorophenylethynylcobalamin (F2PhEtyCbl) was prepared, and its 3D structure was studied in solution and in the crystal. Chemically inert F2PhEtyCbl resisted thermolysis of its Co-C bond at 100 °C, was stable in bright daylight, and also remained intact upon prolonged storage in aqueous solution at room temperature. It binds to the human B12 -processing Enzyme CblC with high affinity (KD =130 nm) in the presence of the cosubstrate glutathione (GSH). F2PhEtyCbl withstood tailoring by CblC, and it also stabilized the ternary complex with GSH. The crystal structure of this inactivated assembly provides first insight into the binding interactions between an antivitamin B12 and CblC, as well as into the organization of GSH and a base-off cobalamin in the active site of this Enzyme.

Keywords

antivitamins; enzyme inhibitors; glutathione; protein crystallography; vitamin B12.

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