In situ complexation of rhodium(II) tetracarboxylates with some derivatives of cysteine and related ligands studied by 1H and 13C nuclear magnetic resonance spectroscopy

Głaszczka, Rafał; Jaźwiński, Jarosław

doi:10.1080/00958972.2016.1238078

Cited by 8 publications

(10 citation statements)

References 23 publications

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“…Significantly, the UV–visible absorption data show an increased absorption at ∼300 nm, corresponding to the well-known cysteine S → Rh ligand-to-metal-charge-transfer (LMCT) band. Similar absorption is also observed with GSH, cysteine, methionine, and other biological thiols 76−82 and confirms the cysteine thiol as the binding moiety involved in the Rh 2 complexation. This LMCT band is very strong and the transition from the blue of the metal solution to the yellow of the protein-bound product can be followed readily with the naked eye.…”

Section: Resultssupporting

confidence: 74%

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Wong

Stillman

2018

ACS Omega

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Anthropogenic sources of xenobiotic metals with no physiological benefit are increasingly prevalent in the environment. The platinum group metals (Pd, Pt, Rh, Ru, Os, and Ir) are found in marine and plant species near urban sources, and are known to bioaccumulate, introducing these metals into the human food chain. Many of these metals are also being used in innovative cancer therapy, which leads to a direct source of exposure for humans. This paper aims to further our understanding of nontraditional metal metabolism via metallothionein, a protein involved in physiologically important metal homeostasis. The aggressive reaction of metallothionein and dirhodium(II) tetraacetate, a common synthetic catalyst known for its cytotoxicity, was studied in detail in vitro. Optical spectroscopic and equilibrium and time-dependent mass spectral data were used to define binding constants for this robust reaction, and molecular dynamics calculations were conducted to explain the observed results.

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Section: Resultssupporting

confidence: 74%

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Wong

Stillman

2018

ACS Omega

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“…48−52 Recently, a 1 H NMR spectrum was reported for a D 2 O solution of S -methylcysteine coordinated to the axial position of Rh 2 (AcO) 4 (mole ratio of 1:1); the broad signals observed in this spectrum were attributed to J (H,H) coupling. 53…”

Section: Discussionmentioning

confidence: 99%

Reactions of Antitumor Active Dirhodium(II) Tetraacetate Rh₂(CH₃COO)₄ with Cysteine and Its Derivatives

2017

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We have combined results from several spectroscopic techniques to investigate the aerobic reactions of Rh 2 (AcO) 4 (AcO – = CH 3 COO – ) with l -cysteine (H 2 Cys) and its derivatives d -penicillamine (3,3′-dimethylcysteine, H 2 Pen), with steric hindrance at the thiol group, and N -acetyl- l -cysteine (H 2 NAC), with its amino group blocked. Previous investigations have shown that antitumor active dirhodium(II) carboxylates may irreversibly inhibit enzymes containing a thiol group at or near their active sites. Also, cysteine, the only thiol-containing proteinogenic amino acid, interacts in vivo with this class of antitumor compounds, but structural information on the products of such reactions is lacking. In the present study, the reactions of Rh 2 (AcO) 4 and H 2 L were carried out in aqueous solutions at the pH of mixing (acidic) and at physiological pH, using the different mole ratios 1:2, 1:4, and 1:6, which resulted in the same products in increasing yields. Electrospray ionization mass spectrometry (ESI-MS) indicates formation of dimeric [Rh III 2 Pen 4 ] 2– or oligomeric {Rh III 2 L 4 } n (L = Cys, NAC) complexes with bridging thiolate groups. Analyses of Rh K edge extended X-ray absorption fine structure (EXAFS) data reveal 3–4 Rh–S and 2–3 Rh–(N/O) bonds around six-coordinated Rh(III) ions at mean distances of 2.33 ± 0.02 and 2.09 ± 0.02 Å, respectively. In the N -acetyl- l -cysteine compound, the Rh III ···Rh III distance 3.10 ± 0.02 Å obtained from the EXAFS spectrum supports trithiolate bridges between the Rh(III) ions, as was also found when using glutathione as ligand. In the cysteine and penicillamine complexes, double thiolate bridges join the Rh(III) ions, with the nonbridging Cys 2– and Pen 2– ligands in tridentate chelating (S,N,O) mode, which is consistent with the Δδ C = 7.3–8.4 ppm shift of the COO – signal in their carbon-13 cross polarization magic angle spinning (CPMAS) NMR spectra. For the penicillamine complex, the 2475.6 eV peak in its S K edge X-ray absorption near edge structure (XANES) spectrum shows partial oxidation, probably caused by peroxide generated from reduction of dissolved O 2 , of thiolato to sulfenato (S=O) groups, which were also identified by ESI-MS for all three {Rh III 2 L 4 } ...

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“…The use of a weaker binding ligand, such as the thioether of methionine, may provide this protection. The reaction of methionine and related thioether complexes with Rh2(OAc)4 has been reported by Pneumatikakis et al and others 37,41,50 . Here we explore the reaction when glutathione is added after methionine is bound to the Rh2(OAc)4.…”

Section: Competition By Glutathione For the Axially-coordinated Methimentioning

confidence: 99%

“…Dirhodium(II) carboxylates and their derivatives are an emerging class of anti-tumour compounds that are described as exhibiting greater potency than cisplatin in vitro [32][33][34][35][36][37][38] . However, significantly, with respect to possible cellular chemistry, rhodium(II) carboxylates bind strongly to sulfur containing compounds 32,33,35,37,[39][40][41] . Indeed, the propensity for these rhodium complexes to deplete intracellular thiols makes them especially useful as radiosensitizers 42,43 .…”

Section: Introductionmentioning

confidence: 99%

Glutathione binding to dirhodium tetraacetate: a spectroscopic, mass spectral and computational study of an anti-tumour compound

et al. 2017

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a See AcknowledgementsGlutathione (γ-L-glutamyl-L-cysteinyl-glycine) is a ubiquitous tripeptide found in all plants and animals. While a major participant in many biological reactions, glutathione has key roles as a metallochaperone, in the reduction of oxidative stress, in the transport of metabolites, and as a cellular thiol source. Here, we report its reaction with , dirhodium(II) tetraacetate (Rh2(OAc)4), a compound with anti-tumour properties, using electrospray ionization mass spectrometry and spectroscopic methods to observe in depth the stoichiometries of the final conjugate. Using computational analysis, we provide the first report of the orbital assignments for the resulting glutatathione-bound product. We also explore the competition by GSH for methionine-bound sites on Rh2(OAc)4 as a method for possible protection of its cellular-based therapeutic activity.

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In situ complexation of rhodium(II) tetracarboxylates with some derivatives of cysteine and related ligands studied by ¹H and ¹³C nuclear magnetic resonance spectroscopy

Cited by 8 publications

References 23 publications

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Reactions of Antitumor Active Dirhodium(II) Tetraacetate Rh₂(CH₃COO)₄ with Cysteine and Its Derivatives

Glutathione binding to dirhodium tetraacetate: a spectroscopic, mass spectral and computational study of an anti-tumour compound

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In situ complexation of rhodium(II) tetracarboxylates with some derivatives of cysteine and related ligands studied by 1H and 13C nuclear magnetic resonance spectroscopy

Cited by 8 publications

References 23 publications

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh2(CH3CO2)4)

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh2(CH3CO2)4)

Reactions of Antitumor Active Dirhodium(II) Tetraacetate Rh2(CH3COO)4 with Cysteine and Its Derivatives

Glutathione binding to dirhodium tetraacetate: a spectroscopic, mass spectral and computational study of an anti-tumour compound

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Product

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In situ complexation of rhodium(II) tetracarboxylates with some derivatives of cysteine and related ligands studied by ¹H and ¹³C nuclear magnetic resonance spectroscopy

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Metallothionein: An Aggressive Scavenger—The Metabolism of Rhodium(II) Tetraacetate (Rh₂(CH₃CO₂)₄)

Reactions of Antitumor Active Dirhodium(II) Tetraacetate Rh₂(CH₃COO)₄ with Cysteine and Its Derivatives