Circular Dichroism of Cytochrome cc' and Cytochrome c'

Imai, Yumiko; Imai, Kazuko; Ikeda, Kiyoshi; Hamaguchi, Kozo; Horio, Takekazu

doi:10.1093/oxfordjournals.jbchem.a129056

Cited by 43 publications

(24 citation statements)

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“…Unfortunately there is as yet no crystallographic information on a CO-ligated species to confirm this suggestion. However, consistent with this suggestion is work done on R. rubrum cytochrome c' which demonstrated that dissociation of the oxidized form of the dimer into monomers is accompanied by significant loss in secondary structure (Akutsu et Imai et al, 1969). The molecular origin of these unusual enthalpy and entropy terms is suggested from the features of the crystal structure of the closely related molecule R. molischianum cytochrome c'.…”

Section: Vamentioning

confidence: 58%

Ligand-controlled dissociation of Chromatium vinosum cytochrome c'

Doyle¹,

Gill²,

Cusanovich³

1986

Biochemistry

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Carbon monoxide binding to Chromatium vinosum ferrocytochrome c' has been studied by high-precision equilibrium methods. In contrast to the CO binding properties of Rhodospirillum molischianum cytochrome c' [Doyle, M. L., Weber, P. C., & Gill, S. J. (1985) Biochemistry 24, 1987-1991], CO binding to C. vinosum cytochrome c' is found to be unusual in the following ways. The binding curve is found to be cooperative with typical Hill coefficients equal to 1.25. The shape of the binding curve is asymmetrical. The heat of CO ligation is measured by two independent methods, both of which yield large endothermic values of approximately 10 kcal [mol of CO(aq)]-1. The overall affinity for CO increases as the concentration of cytochrome c' decreases. These observations suggest the CO binding properties of C. vinosum cytochrome c' are complicated by CO-linked association-dissociation processes. Further investigation by gel filtration chromatography shows that at micromolar concentrations the dimeric state is tightly associated in both the reduced and oxidized forms of the cytochrome but addition of saturating concentrations of CO causes the reduced ligated dimer to dissociate largely into monomers. A model is presented that quantitatively fits the data, involving a ligand-linked dimer-monomer dissociation reaction. In this model, CO binds to the dimer form noncooperatively with an intrinsic affinity constant equal to 5600 +/- 1200 M-1 at 25 degrees C. The unligated dimer form is tightly associated, but addition of CO causes dissociation of the dimer into the monomer with a monomer-dimer association constant equal to 450 +/- 200 M-1.(ABSTRACT TRUNCATED AT 250 WORDS)

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Section: Vamentioning

confidence: 58%

Ligand-controlled dissociation of Chromatium vinosum cytochrome c'

Doyle¹,

Gill²,

Cusanovich³

1986

Biochemistry

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“…14 The pH dependent unique electronic structures and the alkaline spinstate transitions of a number of Fe(III) Cyt c¤ proteins have been discussed. 24,25 The spin state of the heme iron of the type I form at pH 7 has been argued as either Fe(III) high spin, intermediate spin, or a mixture of both. The changes in the optical spectrum as a function of pH have led to the electronic configuration of Fe(III) heme in Cyt c¤ being classified as type I (at pH 7), type II (at pH 10) or type III (at pH 12).…”

Section: Introductionmentioning

confidence: 99%

“…26,27 On the other hand, the exact electronic structures of type II form (pH 10) and type III form (pH 12) are unambiguous, although previously proposed to correspond to pure Fe(III) HS and LS configurations, respectively. 24 While the interconversion between these three forms has been reported to be reversible, the secondary protein structure is reported to be maintained during the type I to type II transition.…”

Section: Introductionmentioning

confidence: 99%

The pH Dependent Protein Structure Transitions and Related Spin-State Transition of Cytochrome c′ from Alcaligenes xylosoxidans NCIMB 11015

Takashina¹,

Tiedemann²,

Unno³

et al. 2016

Bulletin of the Chemical Society of Japan

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The unusual magnetic/spectroscopic properties of Cytochrome c¤ (Cyt c¤) have been discussed, especially concerning the possibility of a quantum mechanically mixed-spin configuration of heme Fe(III). Here, four unique-spin species were identified from the magnetic circular dichroism (MCD) spectra of Cyt c¤ from Alcaligenes xylosoxidans (AxCyt c¤). The electrospray ionization mass spectrometric (ESI-MS) and circular dichroism (CD) spectroscopic data showed the overall conformation of AxCyt c¤ was unchanged, in complete contrast to the drastic changes in the heme MCD spectra over the range of pH 3.5 and 11.8. The pH dependency of ESI-MS, electronic absorption, MCD, and CD spectroscopic properties of AxCyt c¤ enabled us to reveal the undiscovered correlation between the protein-folding state and the electronic structure of the active site as a function of pH. The mechanism of alkaline spin-state transition through the rearrangement of the hydrogen-bonding linkage between Helix C and D is also proposed on the basis of atomic resolution crystal structure analyses (A. Takashina, M. Unno, T. Kohzuma, Chem. Lett. 2015, 44, 268).

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“…electronic absorption (Horio & Kamen, 1961;Imai et al, 1969a), circular dichroism (Imai et al, 1969b;Rawlings et al, 1977), resonance Raman (Strekas & Spiro, 1974; Kitagawa et al, 1977), and nuclear magnetic resonance (Emptage et al, 1981; La Mar et al, 1981) spectroscopies. In the case of the oxidized state, type I characterized by the Soret band at 390 nm appears at acidic and neutral pH.…”

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confidence: 99%