title: Insights on the mechanism of thioredoxin reductase inhibition by gold N-heterocyclic carbene compounds using the synthetic linear selenocysteine containing C-terminal peptide hTrxR(488-499): an ESI-MS investigation.
abstract: Gold-based drugs typically behave as strong inhibitors of the enzyme thioredoxin reductase (hTrxR), possibly as the consequence of direct Gold(I) coordination to its active site selenocysteine. To gain a deeper insight into the molecular basis of enzyme inhibition and prove gold-selenocysteine coordination, the reactions of three parent Gold(I) NHC compounds with the synthetic C-terminal dodecapeptide of hTrxR containing Selenocysteine at position 498, were investigated by electrospray ionization mass spectrometry (ESI-MS). Formation of 1:1 Gold-peptide adducts, though in highly different amounts, was demonstrated in all cases. In these adducts the same [Au-NHC](+) moiety is always associated to the intact peptide. Afterward, tandem MS experiments, conducted on a specific Gold-peptide complex, pointed out that Gold is coordinated to the selenolate group. The relatively large strength of the Gold-selenolate coordinative bond well accounts for potent enzyme inhibition typically afforded by these Gold(I) compounds. In a selected case, the time course of enzyme inhibition was explored. Interestingly, enzyme inhibition turned out to show up very quickly and reached its maximum just few minutes after mixing. Overall, the present results offer some clear insight into the process of thioredoxin reductase inhibition by Gold-based compounds.
authors: Interdepartmental Laboratory of Peptide & Protein Chemistry & Biology (PeptLab), University of Florence, 50019 Sesto Fiorentino, Firenze, Italy; Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Firenze, Italy.
authors: Alessandro
authors: A
authors: Pratesi
authors: Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
authors: Chiara
authors: C
authors: Gabbiani
authors: Mass Spectrometry Centre (CISM), University of Florence, Via U. Schiff 6, 50019 Sesto Fiorentino, Firenze, Italy.
authors: Elena
authors: E
authors: Michelucci
authors: Interdepartmental Laboratory of Peptide & Protein Chemistry & Biology (PeptLab), University of Florence, 50019 Sesto Fiorentino, Firenze, Italy; Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Firenze, Italy.
authors: Mauro
authors: M
authors: Ginanneschi
authors: Interdepartmental Laboratory of Peptide & Protein Chemistry & Biology (PeptLab), University of Florence, 50019 Sesto Fiorentino, Firenze, Italy; Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Firenze, Italy.
authors: Anna Maria
authors: AM
authors: Papini
authors: Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Beethovenstr. 55, 38106 Braunschweig, Germany.
authors: Riccardo
authors: R
authors: Rubbiani
authors: Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, Beethovenstr. 55, 38106 Braunschweig, Germany.
authors: Ingo
authors: I
authors: Ott
authors: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Firenze, Italy; Laboratory of Metals in Medicine (METMED), University of Florence, 50019 Sesto Fiorentino, Firenze, Italy. Electronic address: luigi.messori@unifi.it.
authors: Luigi
authors: L
authors: Messori
mesh_terms: D000595:Amino Acid Sequence; D056831:Coordination Complexes / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry*; D017612:Gold Compounds / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry; D009842:Oligopeptides / Q000737:chemistry; D017279:Selenocysteine / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D013880:Thioredoxin-Disulfide Reductase / Q000037:antagonists & inhibitors / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D004791:Enzyme Inhibitors; D017612:Gold Compounds; D006571:Heterocyclic Compounds; D009842:Oligopeptides; D017279:Selenocysteine; D013880:Thioredoxin-Disulfide Reductase
keywords: ESI-MS; Gold NHC carbenes; Synthetic peptide; Thioredoxin reductase