Intramolecular electron transfer between Ru(I) and Ru(III) and the heme iron of cytochrome c labeled with ruthenium(II) polypyridine complexes

Heacock, Donald H.; Harris, Michele R.; Durham, Bill; Millett, Francis

doi:10.1016/0020-1693(94)04078-8

Cited by 7 publications

(4 citation statements)

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“…It has been suggested that Ru + → Fe 3+ reactions are so exergonic that formation of an electronically excited species (at lower driving force) is faster than the (highly inverted) reaction directly to ground-state Ru 2+ −Fe 2+ those for ferrocytochrome c are not: the origin of the transition to the 1 MLCT [Fe(dπ) → P(π*), P = porphyrin] excited state is roughly 1.3 eV and the 3 MLCT state is estimated at ∼1.05 eV .…”

Section: Resultsmentioning

confidence: 99%

“…36 It has been suggested that Ru + f Fe 3+ reactions are so exergonic that formation of an electronically excited species (at lower driving force) is faster than the (highly inverted) reaction directly to ground-state Ru 2+ -Fe 2+ . 37 Although the lowest Ru 2+ excited states are out of reach (g1.9 eV), 38 those for ferrocytochrome c are not: the origin of the transition to the 1 MLCT [Fe(dπ) f P(π*), P ) porphyrin] excited state is roughly 1.3 eV 39 and the 3 MLCT state is estimated at ∼1.05 eV. 40 Indeed, the rates predicted for the Ru + -Fe 3+ f Ru 2+ -*Fe 2+ ( 3 MLCT) reactions of complexes VI and IV (Figure 1: 5 f 7) are close to those observed for Ru + f Fe 3+ ET (Figure 3, bottom).…”

Section: Resultsmentioning

confidence: 99%

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Rates of Heme Oxidation and Reduction in Ru(His33)cytochrome c at Very High Driving Forces

et al. 1996

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The rates of Ru(His33)cytochrome c electron-transfer (ET) reactions have been measured over a driving-force range of 0.59 to 1.89 eV. The driving-force dependence of Fe2+ → Ru3+ ET in RuL2(im)(His33)cyt c [L = 2,2‘-bipyridine (bpy), 4,4‘,5,5‘-tetramethyl-2,2‘-bipyridine (4,4‘,5,5‘-(CH3)4-bpy), 4,4‘-dimethyl-2,2‘-bipyridine (4,4‘-(CH3)2-bpy), 4,4‘-bis(N-ethylcarbamoyl)-2,2‘-bipyridine (4,4‘-(CONH(C2H5))2-bpy), 1,10-phenanthroline (phen); im = imidazole] is well described by semiclassical ET theory with k max = 2.7 × 106 s-1 (HAB = 0.095 cm-1) and λ = 0.74 eV. As predicted by theory, the rate of an exergonic (−ΔG° = 1.3 eV) heme reduction reaction, *Ru2+(bpy)2(im)(His) → Fe3+, falls in the inverted region (k = 2.0 × 105 s-1). In contrast, the rates of three highly exergonic heme reductions, *Ru2+(phen)2(CN)(His) → Fe3+ (2.0 × 105 s-1; 1.40 eV), Ru+(4,4‘-(CONH(C2H5))2-bpy)2(im)(His) → Fe3+ (2.3 × 105 s-1; 1.44 eV), and Ru+(phen)2(CN)(His) → Fe3+ (4.5 × 105 s-1; 1.89 eV), are much higher than expected for reactions directly to ground-state products. Agreement with theory is greatly improved by assuming that an electronically excited ferroheme (Fe2+ → *Fe2+; ∼ 1.05 eV) is the initial product in each of these reactions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Rates of Heme Oxidation and Reduction in Ru(His33)cytochrome c at Very High Driving Forces

et al. 1996

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“…Heme Fe(III) can be reduced by Ru(II*) in steps k 1 and k 6 using a sacrificial donor (D) such as aniline. We have also found that a donor with a lower potential such as N,N-dimethylaminobenzoate can directly reduce Ru(II*) in step k 5 , followed by electron transfer from Ru(I) to heme Fe(III) in step k 4 (47). One of the advantages of the cysteine labeling chemistry is that all three chelating ligands can be varied to tune the redox properties of the ruthenium complex to optimize photochemical production of the desired products.…”

Section: Design Of Ruthenium Complexes For Photoinitiation Of Electro...mentioning

confidence: 89%

Design of Photoactive Ruthenium Complexes To Study Interprotein Electron Transfer

Millett

Durham

2002

Biochemistry

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“…Electron transfer processes in proteins have also been studied with the aid of photoredox-active (bipyridine)ruthenium complexes covalently attached to the biomolecule. Site-specific functionalized lysine residues were used as tris(2,2‘-bipyridine)ruthenium-binding sites for the study of photoinduced electron transfer in cytochromes and cytochrome c oxidase. − In these approaches, a bipyridine ligand was attached via an amide bond to the lysine side chain.…”

Section: Introductionmentioning

confidence: 99%

Novel Building Blocks for Biomimetic Assemblies. Synthesis, Characterization, and Spectroscopic and Electrochemical Properties of New Bidentate Ligands Derived from Lysine and Cysteine and Their Complexes with Bis(2,2‘-bipyridine)ruthenium(II)

and

Eldik

1996

Inorg. Chem.

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Synthetic amino acids suitable for the assembly of small, redox-active metallopeptides are described. N α-((1,1-Dimethylethoxy)carbonyl)-N ε-(2-pyridylmethyl)-l-lysine (1), N α-acetyl-S-(2-pyridylmethyl)-l-cysteine (2), and N α-acetyl-S-(2-(2-pyridyl)ethyl)-l-cysteine (3) have been synthesized by alkylation of the N α-protected amino acids. Their [Ru(bipy)2]2+ complexes [(bipy)2Ru(BocLysCH2py)]2+ (4), [(bipy)2Ru(AcCysCH2py)]2+ (5), and [(bipy)2Ru(AcCys(CH2)2py)]2+ (6) have been prepared by reactions of the ligands with [Ru(bipy)2Cl2]. On the basis of 1H-NMR spectroscopy, 4−6 can be described best as trans-tetrapyridine complexes with the lysine amino N atom and the cysteine S atom occupying one of the apical positions. It was shown by luminescence spectroscopy that 4 can serve as a possible photoredox-active module for the construction of photochemically active peptides. The redox properties of the complexes are described with the aid of the Lever parameters. It was demonstrated that the amino acid ligands in 5 and 6 can be viewed as methionine units. Particularly interesting is the unique redox chemistry of 4. Upon metal oxidation, a two-electron ligand oxidation occurred, followed by fast hydrolytic cleavage of the lysine−methylpyridine N−C bond. The physical and chemical properties of the compounds are discussed in terms of future applications in biomimetic chemistry such as the activation of small molecules.

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Intramolecular electron transfer between Ru(I) and Ru(III) and the heme iron of cytochrome c labeled with ruthenium(II) polypyridine complexes

Cited by 7 publications

References 23 publications

Rates of Heme Oxidation and Reduction in Ru(His33)cytochrome c at Very High Driving Forces

Rates of Heme Oxidation and Reduction in Ru(His33)cytochrome c at Very High Driving Forces

Design of Photoactive Ruthenium Complexes To Study Interprotein Electron Transfer

Novel Building Blocks for Biomimetic Assemblies. Synthesis, Characterization, and Spectroscopic and Electrochemical Properties of New Bidentate Ligands Derived from Lysine and Cysteine and Their Complexes with Bis(2,2‘-bipyridine)ruthenium(II)

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