Interaction of [Rh₂(O₂CCH₃)₄(H₂O)₂] and [Rh₂(O₂CCH(OH)Ph)₂(phen)₂(H₂O)₂](O₂C‐CH(OH)Ph)₂ With Sulfhydryl Compounds and Ceruloplasmin

Abstract

The interaction of binuclear rhodium(lI) complexes Rh2(OOCCH3)4(H20)2], [Rh2{OOCCH(OH)Ph}2(phen)2(H20)2] {OOCCH(OH)Ph}2, [Rh2(OOCCH3)2(bpy)2(H20)2](OOCCH3)2 and [Rh2Cl2(OOCMe)2(bpy)2](3H20) with ceruloplasmin, cysteine, glutathione and coenzyme A have been investigated using UV-Vis and CD spectroscopies. The complexes containing phen or bpy at pH 7.4 and 4.0 are readily reduced with sulfhydryl compounds, while rhodium(II) acetate is relatively stable in these conditions. Complex [Rh2{OOCCH(OH)Ph}2(phen)2(H20)2] strongly changes structure of ceruloplasmin leading to the decrease of x-helix content and loss of oxidase activity.

Methionine Binding to Dirhodium(II) Tetraacetate

“…The electronic absorption spectra reported for Rh 2 (AcO) 4 –methionine mixtures have often been limited to the visible region (400-800 nm). 29, 30, 32 Figure 2 ( top ) shows the UV-vis spectra of a 2.00 mM aqueous solution of Rh 2 (AcO) 4 ( 1 ), and its reaction mixtures with DL -methionine in mole ratios 1:2 (solution A ) and 1:10 (solution B ). The inset displays a blue shift for the absorption peak maximum in the visible region, from λ max = 584 nm for [Rh 2 (AcO) 4 (H 2 O) 2 ], to 556 and 540 nm as the amount of HMet in solution increases.…”

“…Later, Jakimowicz et al monitored the same reaction at pH 7.4 via UV-vis spectroscopy over 5 days, and confirmed the formation of [Rh 2 (AcO) 4 ( S -HMet) 1-2 ] based on “the blue shift of the band I and strong increase of absorption in the range of 430-350 nm”, which was assigned as S → Rh charge transfer. 30 Band I has been attributed to the π*(Rh 2 ) → σ*(Rh 2 ) transition in [Rh 2 (AcO) 4 (H 2 O) 2 ]. 31 More recently, 1 H NMR spectroscopy was used to confirm the S -coordination of HMet to Rh 2 (AcO) 4 in D 2 O by comparing experimental data with calculated 1 H-NMR chemical shifts.…”

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

“…Spectroscopic studies of glutathione binding to dirhodium tetraacetate and related compounds have been reported previously by Jakimowicz et al 47 By adding molar equivalents of GSH to Rh2(OAc)4, the authors surmised that the stoichiometric ratio, GSH: Rh2(OAc)4, for the final conjugate was 2:1. Unfortunately, optical spectra provide limited information, as the spectral data results from an averaged signal of all the chromophores present.…”

Inhibiting prolyl isomerase activity by hybrid organic–inorganic molecules containing rhodium(II) fragments

“…4). A negative control, Rh 2 (OAc) 4 , had no effect on the rate of the reaction at concentrations up to 25 lM.…”

“…22,23 They bind not only thiol, thioether, and imidazole side chains, but also other weaker Lewis-bases such as the carboxylate side chain of glutamate. 24,25 We previously reported that methionine, glutamate, and histidine interact with the rhodium(II) center in a coil-coil heterodimer, stabilizing an otherwise weak supramolecular assembly. 26,27 From this precedent, rhodium(II) metallopeptides ligands for PDZ were designed that utilize coordination to a specific histidine residue (PDZ His301) to afford significantly tighter binding (40-80 fold).…”