Conformation of ferricytochrome c. IV. Relationship between optical absorption and protein conformation

Shechter, Emanuel; Saludjian, P.

doi:10.1002/bip.1967.360050812

Cited by 200 publications

(106 citation statements)

References 12 publications

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“…the sixth heme coordination site is unoccupied or contains a weak ligand, such as a hydroxide ion), and the weak charge-transfer band at 695 nm, which correlates with the presence of a native Met80 sulfur-iron bond. 41,43 Finally, we measured the GuHCl-induced changes in tryptophan fluorescence, which are dominated by resonant energy transfer to the heme (a highly efficient fluorescence quencher), and thus provide Table 1. The intrinsic CD signal of the N and I-states was assumed to be independent of GuHCl concentration.…”

Section: K1mentioning

confidence: 99%

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Latypov

Cheng

Roder

et al. 2006

Journal of Molecular Biology

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Although the denaturant-induced unfolding transition of cytochrome c was initially thought to be a cooperative process, recent spectroscopic studies have shown deviations from two-state behavior consistent with accumulation of an equilibrium intermediate. However, little is known about the structural and thermodynamic properties of this state, and whether it is stabilized by the presence of non-native heme ligands. We monitored the reversible denaturant-induced unfolding equilibrium of oxidized horse cytochrome c using various spectroscopic probes, including fluorescence, near and far-UV CD, heme absorbance bands in the Soret, visible and near-IR regions of the spectrum, as well as 2D NMR. Global fitting techniques were used for a quantitative interpretation of the results in terms of a three-state model, which enabled us to determine the intrinsic spectroscopic properties of the intermediate. A well-populated intermediate was observed in equilibrium experiments at pH 5 using either guanidine-HCl or urea as a denaturant, both for wild-type cytochrome c as well as an H33N mutant chosen to prevent formation of non-native Hisheme ligation. For a more detailed structural characterization of the intermediate, we used 2D 1 H-15 N correlation spectroscopy to follow the changes in peak intensity for individual backbone amide groups. The equilibrium state observed in our optical and NMR studies contains many native-like structural features, including a well-structured a-helical subdomain, a short Trp59-heme distance and solvent-shielded heme environment, but lacks the native Met80 sulfur-iron linkage and shows major perturbations in side-chain packing and other tertiary interactions. These structural properties are reminiscent of the A-state of cytochrome c, a compact denatured form found under acidic high-salt conditions, as well as a kinetic intermediate populated at a late stage of folding. The denaturant-induced intermediate also resembles alkaline forms of cytochrome c with altered heme ligation, suggesting that disruption of the native methionine ligand favors accumulation of structurally analogous states both in the presence and absence of non-native ligands.

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Section: K1mentioning

confidence: 99%

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Latypov

Cheng

Roder

et al. 2006

Journal of Molecular Biology

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“…2) (Fig.2) [19,20]. En fait, il semble assez illusoire de vouloir estimer les proportions cle ces differentes structures puisque le cytochrome c prbsente ces mdmes minima [21,22] alors qu'il ne possbde pas de rbgions en structure a [23,24].…”

Section: Dichroisme Dam Le Visible Et Le P R O C H Ultra-violet Apo-nunclassified

“…Pour les cytochromes c extraits de divers organismes, deux bandes dichroi'ques positives vers 250-270 nm [21,22,26,27] ont 6th attribukes 1221 au complexe fer-porphyrine-histidine. Ces bandes sont absentes chez le noyau cytochromique b,, bien qu'une histidine soit Bgalement impliquee dans la fixation de l'hbme [28].…”

Section: Dichroisme Dam Le Visible Et Le P R O C H Ultra-violet Apo-nunclassified

Étude par dichroïsme circulaire des interactions hème‐flavine‐protéine dans le cytochrome b₂ (l‐lactate oxydoréductase) de la levure

Iwatsubo

Risler

1969

European Journal of Biochemistry

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The circular dichroism spectra of bakers' yeast L-lactate dehydrogenase and some of its derivatives (without flavin andlor heme) have been investigated in order to obtain some information about the interactions between the prosthetic chromophores or between these chromophores and the protein moiety.The following derivatives were studied: (a) the cytochrome b, (flavohemoprotein), (b) the apocytochrome b, (following FMN removal), (c) the noyau cytochromique b, (low molecular weight core isolated following proteolytic degradation), (d) the apo-noyau cytochromique b, (obtained by removal of the heme from the latter).It is shown that the circular dichroism spectra of the protein moieties in the ultraviolet region I n conclusion there appears to be no prosthetic group-protein interaction detectable by circular dichroism measurements, i. e. no important modification of the peptide bond geometry occurs when the flavin is removed from the enzyme or when the oxido-reduction state of the heme is varied. However, a strong effect is exerted by the flavin on the symmetry of the heme environment, this effect being probably an indirect one, via the protein moiety, as discussed in this paper.

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“…In the visible spectra, a peak at 695 nm from the ferric form, which indicates axial coordination between the heme-iron and methionine-sulfur, 27) disappeared in dCyt c, so that the heme probably was in a 5-coordinated form (Fig. 6(A)).…”

Section: )mentioning

confidence: 99%

Appearance of Nitrite Reducing Activity of Cytochromecupon Heat Denaturation

Yamada

Suruga

Ogawa

et al. 2002

Bioscience, Biotechnology, and Biochemistry

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Conformation of ferricytochrome c. IV. Relationship between optical absorption and protein conformation

Cited by 200 publications

References 12 publications

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Étude par dichroïsme circulaire des interactions hème‐flavine‐protéine dans le cytochrome b₂ (l‐lactate oxydoréductase) de la levure

Appearance of Nitrite Reducing Activity of Cytochromecupon Heat Denaturation

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Conformation of ferricytochrome c. IV. Relationship between optical absorption and protein conformation

Cited by 200 publications

References 12 publications

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Structural Characterization of an Equilibrium Unfolding Intermediate in Cytochrome c

Étude par dichroïsme circulaire des interactions hème‐flavine‐protéine dans le cytochrome b2 (l‐lactate oxydoréductase) de la levure

Appearance of Nitrite Reducing Activity of Cytochromecupon Heat Denaturation

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Étude par dichroïsme circulaire des interactions hème‐flavine‐protéine dans le cytochrome b₂ (l‐lactate oxydoréductase) de la levure