2020
DOI: 10.1039/d0cb00115e
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Met80 and Tyr67 affect the chemical unfolding of yeast cytochromec: comparing the solutionvs.immobilized state

Abstract: The motional regime affects the unfolding propensity and axial heme coordination of the Met80Ala and Met80Ala/Tyr67Ala variants of yeast iso-1 cytochrome c.

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Cited by 6 publications
(13 citation statements)
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References 166 publications
(298 reference statements)
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“…[42] At high DMSO concentrations, the observed major structural effects could include a change in axial heme iron ligation, such as the replacement of the (6th) hydroxide ion (that binds to the heme iron of M80 A in water) with a lysine or a histidine residue. Analogous transitions involving the 6th axial ligand switch were observed previously for freely diffusing M80 A in the presence of a denaturing agent (urea), [60] for the hydrophobically electrode-immobilized protein or in the presence of cardiolipin liposomes. [61] Alternatively, such an effect could arise from major conformational changes that can severely modify the surroundings of the heme and, consequently, the redox properties of the metal center.…”
Section: Dmso-induced Conformational Changessupporting
confidence: 76%
“…[42] At high DMSO concentrations, the observed major structural effects could include a change in axial heme iron ligation, such as the replacement of the (6th) hydroxide ion (that binds to the heme iron of M80 A in water) with a lysine or a histidine residue. Analogous transitions involving the 6th axial ligand switch were observed previously for freely diffusing M80 A in the presence of a denaturing agent (urea), [60] for the hydrophobically electrode-immobilized protein or in the presence of cardiolipin liposomes. [61] Alternatively, such an effect could arise from major conformational changes that can severely modify the surroundings of the heme and, consequently, the redox properties of the metal center.…”
Section: Dmso-induced Conformational Changessupporting
confidence: 76%
“…From the larger effect exerted by the medium on M80A in solution vs. the immobilized species for %DMSO > 10, it appears that the latter interaction is affected to a lesser extent by the water/DMSO ratio than the electrostatic effects due to the protein charges in freely diffusing conditions. The discontinuity observed around 30% DMSO might be due, at least in part, to a structural transition, probably involving the substitution of axial OH − ligand by a second histidine [ 30 , 37 , 38 , 39 , 49 ]. As for the slopes observed at the lowest DMSO concentrations, one possibility is that the water solvates DMSO making it less effective in modulating the apparent dielectric constant, while in the same concentration range the interaction between the organic molecules and the SAM headgroups is more relevant in modulating the thermodynamic parameters.…”
Section: Resultsmentioning
confidence: 99%
“…Insight into the effects of DMSO on the overall structure of the M80A cytc mutant was gained from the CD spectra in the near UV region (250–350 nm) and by fluorescence emission by Trp59 ( Figure 7 a,c, respectively). The near UV CD spectrum features two narrow minima at 282.5 and 289 nm (ascribable to transitions that involve the Trp59 lateral chain) [ 37 , 73 , 74 , 75 , 76 ] and three maxima between 250 and 270 nm (arising from transitions involving the Tyr residues side chains and the heme group [ 37 , 73 , 75 ]. Such spectrum is basically superimposable to that of wt cytc in the absence of DMSO, confirming that the three-dimensional structure of the protein is not significantly affected by the substitution of the Fe-coordinating methionine with a non-coordinating alanine [ 37 , 74 , 75 , 77 ].…”
Section: Resultsmentioning
confidence: 99%
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