title: A click chemistry approach identifies target proteins of xanthohumol.
abstract: METHODS
  Many phytochemicals with beneficial pharmacological properties contain electrophilic sites, e.g. α,β-unsaturated carbonyl (enone) groups. There is increasing evidence that many biological effects of electrophilic compounds depend on covalent conjugation to reactive protein thiols. For example, the reaction of electrophiles with cysteinyl residues of the sensor protein Keap1 activates the cell-protective Nrf2 response. Thus it is of interest to identify more generally the proteins to which small molecule electrophiles bind covalently.
  
  
  RESULTS
  Here we use a Click chemistry approach to identify target proteins of the chemopreventive phytochemical xanthohumol (XN), an enone-containing chalcone from hops (Humulus lupulus L.). Using an alkynylated analog of XN (XN-alkyne), we purified covalent protein-electrophile conjugates from cell lysates. We confirm the previously described conjugation of XN to Keap1. One of the newly identified candidate target proteins is glucose-6-phosphate dehydrogenase (G6PDH). We confirm that XN attenuates intracellular G6PDH activity at low micromolar concentrations.
  
  
  CONCLUSIONS
  We find support for the notion that XN modulates multiple pathways and processes by covalent modification of proteins with reactive cysteines.
authors.affiliation: Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.|Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Lidia
authors.initials: L
authors.lastname: Brodziak-Jarosz
authors.affiliation: Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.
authors.forename: Yuuta
authors.initials: Y
authors.lastname: Fujikawa
authors.affiliation: Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pastor-Flores
authors.affiliation: Institute of Organic Chemistry, University of Regensburg, Regensburg, Germany.
authors.forename: Sonay
authors.initials: S
authors.lastname: Kasikci
authors.affiliation: Institute of Organic Chemistry, University of Regensburg, Regensburg, Germany.|Institute of Pharmaceutical Biology, University of Regensburg, Regensburg, Germany.
authors.forename: Petr
authors.initials: P
authors.lastname: Jirásek
authors.affiliation: Institute of Organic Chemistry, University of Regensburg, Regensburg, Germany.|Institute of Pharmaceutical Biology, University of Regensburg, Regensburg, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Pitzl
authors.affiliation: Division of Preventive Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Owen
authors.affiliation: Core Facility, Molecular Structure Analysis, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Karel D
authors.initials: KD
authors.lastname: Klika
authors.affiliation: Division of Epigenomics and Cancer Risk Factors, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Clarissa
authors.initials: C
authors.lastname: Gerhäuser
authors.affiliation: Institute of Organic Chemistry, University of Regensburg, Regensburg, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Amslinger
authors.affiliation: Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, Heidelberg, Germany.
authors.forename: Tobias P
authors.initials: TP
authors.lastname: Dick
mesh_terms: D000480:Alkynes / Q000737:chemistry / Q000378:metabolism; D057930:Click Chemistry / Q000379:methods*; D003543:Cysteamine / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D005954:Glucosephosphate Dehydrogenase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D000072019:Kelch-Like ECH-Associated Protein 1 / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011427:Propiophenones / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D012995:Solubility; D021241:Spectrometry, Mass, Electrospray Ionization; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D000480:Alkynes; D005419:Flavonoids; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D011427:Propiophenones; D011506:Proteins; D013438:Sulfhydryl Compounds; D003543:Cysteamine; D005954:Glucosephosphate Dehydrogenase; C104536:xanthohumol
keywords: Click chemistry; Electrophilic compounds; Keap1-Nrf2 pathway; Protein thiols; Xanthohumol