The heme iron coordination of unfolded ferric and ferrous cytochrome c in neutral and acidic urea solutions. Spectroscopic and electrochemical studies

Fedurco, Milan; Augustyński, Jan; Indiani, Chiara; Smulevich, Giulietta; Antalı́k, Marián; Bánó, M.; Sedlák, Erik; Glascock, Mary C.; Dawson, John H.

doi:10.1016/j.bbapap.2004.09.013

Cited by 50 publications

(86 citation statements)

References 41 publications

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“…The small decrease in E°0 value observed increasing the urea concentration is consistent, however, with the progressive substitution of the lysine with the histidine. At [urea] C 8 M the His-Lys form is no more present and the bishistidinate species is the only form present in the solution [14,[22][23][24]. The poor reversibility of wave II (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…The appearance of a new wave (wave II) at potentials approximately 0.5 V lower than that of wave I (Fig. 1, Tables 2, 3 and 4) most likely corresponds to the formation of a new conformer with an altered heme iron axial coordination [14,[22][23][24].…”

Section: Discussionmentioning

confidence: 99%

“…The properties of wave II suggest its assignment to a species subjected to substitution of the axial ligand Met80 by a harder base such as a nitrogen atom of a histidine or lysine residue. At high urea concentrations ([urea] C 8 M) it is well established that a bishistidinate form of the cytochrome c is the prevailing species [14,22,23] while at low urea concentrations (4 \ [urea] \ 8) an equilibrium between a His-Lys form and the bis-histidinate one has been proposed [14]. The more basic character of the nitrogen atom(s) of the histidine (or lysine) ligand compared to the thioether sulfur of the native methionine stabilizes the ferriheme and is likely to be mainly responsible for the dramatic decrease in E°0 value of wave II as compared to wave I.…”

Section: Discussionmentioning

confidence: 99%

“…Recent resonance Raman studies have shown that the heme of ferricytochrome c at high urea concentration and at neutral pH features a bis-histidine ligation [22]. In the present work, the redox thermodynamics of this protein variant has been characterized and compared with that of the native form.…”

Section: Introductionmentioning

confidence: 99%

“…For this reason, several studies have been devoted to the characterization of ET processes of cytochrome c in solution in the presence of denaturant agents [22][23][24], and recently the structural perturbation in the heme cavity due to the unfolding processes was investigated through analysis of the reorganization energy k [25].…”

Section: Introductionmentioning

confidence: 99%

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Redox thermodynamics of cytochromes c subjected to urea induced unfolding

et al. 2009

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The thermodynamics of the electron transfer (ET) process for beef heart and yeast cytochromes c and the Lys72Ala/Lys73Ala/Lys79Ala mutant of the latter species subjected to progressive urea-induced unfolding was determined electrochemically. The results indicate the presence of at least three protein forms which were assigned to a low-temperature and a high-temperature HisMet intermediate species and a bis-histidinate form (although the presence of a His-Lys form cannot be excluded). The much lower E°0 value of the bis-histidinate conformer as compared to His-Met ligated species is largely determined by the enthalpic contribution induced by axial ligand substitution. The biphasic E°0 versus T profile for the His-Met species is due to a difference in reduction entropy between the conformers at low and high temperatures. Enthalpy-entropy compensation phenomena for the reduction reaction at varying urea concentration for all the forms of the investigated cytochromes c were addressed and discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Redox thermodynamics of cytochromes c subjected to urea induced unfolding

et al. 2009

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Enzymatic activity and thermal stability of metallo proteins in hydrated ionic liquids

2010

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Hydrated choline dihydrogen phosphate (Hy[ch][dhp]) containing 30 wt% water was investigated as a novel protein solvent. The Hy[ch][dhp] dissolved some metallo proteins (cytochrome c, peroxidase, ascorbate oxidase, azurin, pseudoazurin and fructose dehydrogenase) without any modification. These proteins retained the surroundings of the active site after dissolution in Hy[ch][dhp]. Some metallo proteins were found to retain their activity in the Hy[ch][dhp].

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Unexpected improvement in stability and utility of cytochrome c by solution in biocompatible ionic liquids

Fujita¹,

Forsyth²,

MacFarlane³

et al. 2006

Biotech & Bioengineering

173

169

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Proteins generally are only stable in vitro for short periods of time. This results in challenges during isolation and purification of recombinant proteins and reduces the shelf life of protein-based pharmaceuticals. Here we show that certain novel, biocompatible ionic liquids provide a stabilizing solvent for proteins, for example, cytochrome c, such that structure and activity are maintained even after 6 months of storage at room temperature. Normally, this protein would be rendered inactive after only 1 week in buffered aqueous solution. The effect of the ionic liquid solvent appears to be related to protection against hydrolysis.

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The heme iron coordination of unfolded ferric and ferrous cytochrome c in neutral and acidic urea solutions. Spectroscopic and electrochemical studies

Cited by 50 publications

References 41 publications

Redox thermodynamics of cytochromes c subjected to urea induced unfolding

Redox thermodynamics of cytochromes c subjected to urea induced unfolding

Enzymatic activity and thermal stability of metallo proteins in hydrated ionic liquids

Unexpected improvement in stability and utility of cytochrome c by solution in biocompatible ionic liquids

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