The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics
Here we investigated the effect of electrostatic interactions and of protein tyrosine nitration of mammalian cytochrome c on the dynamics of the so-called alkaline transition, a pH- and redox-triggered conformational change that implies replacement of the axial ligand Met80 by a Lys residue. Using a...
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2019
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v665_n_p96_OviedoRouco http://hdl.handle.net/20.500.12110/paper_00039861_v665_n_p96_OviedoRouco |
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paper:paper_00039861_v665_n_p96_OviedoRouco2023-06-08T14:25:07Z The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics Alkaline transition Cytochrome c Protein electron transfer Protein nitration Protein spectroelectrochemistry Time-resolved SERR cytochrome c ligand tyrosine alkalinity Article cellular distribution chemical reaction kinetics conformational transition cyclic potentiometry deprotonation electrochemical analysis model molecular dynamics nitration oxidation reduction reaction pH pKa priority journal protein conformation Raman spectrometry reaction analysis static electricity surface property Here we investigated the effect of electrostatic interactions and of protein tyrosine nitration of mammalian cytochrome c on the dynamics of the so-called alkaline transition, a pH- and redox-triggered conformational change that implies replacement of the axial ligand Met80 by a Lys residue. Using a combination of electrochemical, time-resolved SERR spectroelectrochemical experiments and molecular dynamics simulations we showed that in all cases the reaction can be described in terms of a two steps minimal reaction mechanism consisting of deprotonation of a triggering group followed by ligand exchange. The pK a alk values of the transition are strongly modulated by these perturbations, with a drastic downshift upon nitration and an important upshift upon establishing electrostatic interactions with a negatively charged model surface. The value of pK a alk is determined by the interplay between the acidity of a triggering group and the kinetic constants for the forward and backward ligand exchange processes. Nitration of Tyr74 results in a change of the triggering group from Lys73 in WT Cyt to Tyr74 in the nitrated protein, which dominates the pK a alk downshift towards physiological values. Electrostatic interactions, on the other hand, result in strong acceleration of the backward ligand exchange reaction, which dominates the pK a alk upshift. The different physicochemical conditions found here to influence pK a alk are expected to vary depending on cellular conditions and subcellular localization of the protein, thus determining the existence of alternative conformations of Cyt in vivo. © 2019 Elsevier Inc. 2019 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v665_n_p96_OviedoRouco http://hdl.handle.net/20.500.12110/paper_00039861_v665_n_p96_OviedoRouco |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Alkaline transition Cytochrome c Protein electron transfer Protein nitration Protein spectroelectrochemistry Time-resolved SERR cytochrome c ligand tyrosine alkalinity Article cellular distribution chemical reaction kinetics conformational transition cyclic potentiometry deprotonation electrochemical analysis model molecular dynamics nitration oxidation reduction reaction pH pKa priority journal protein conformation Raman spectrometry reaction analysis static electricity surface property |
| spellingShingle |
Alkaline transition Cytochrome c Protein electron transfer Protein nitration Protein spectroelectrochemistry Time-resolved SERR cytochrome c ligand tyrosine alkalinity Article cellular distribution chemical reaction kinetics conformational transition cyclic potentiometry deprotonation electrochemical analysis model molecular dynamics nitration oxidation reduction reaction pH pKa priority journal protein conformation Raman spectrometry reaction analysis static electricity surface property The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| topic_facet |
Alkaline transition Cytochrome c Protein electron transfer Protein nitration Protein spectroelectrochemistry Time-resolved SERR cytochrome c ligand tyrosine alkalinity Article cellular distribution chemical reaction kinetics conformational transition cyclic potentiometry deprotonation electrochemical analysis model molecular dynamics nitration oxidation reduction reaction pH pKa priority journal protein conformation Raman spectrometry reaction analysis static electricity surface property |
| description |
Here we investigated the effect of electrostatic interactions and of protein tyrosine nitration of mammalian cytochrome c on the dynamics of the so-called alkaline transition, a pH- and redox-triggered conformational change that implies replacement of the axial ligand Met80 by a Lys residue. Using a combination of electrochemical, time-resolved SERR spectroelectrochemical experiments and molecular dynamics simulations we showed that in all cases the reaction can be described in terms of a two steps minimal reaction mechanism consisting of deprotonation of a triggering group followed by ligand exchange. The pK a alk values of the transition are strongly modulated by these perturbations, with a drastic downshift upon nitration and an important upshift upon establishing electrostatic interactions with a negatively charged model surface. The value of pK a alk is determined by the interplay between the acidity of a triggering group and the kinetic constants for the forward and backward ligand exchange processes. Nitration of Tyr74 results in a change of the triggering group from Lys73 in WT Cyt to Tyr74 in the nitrated protein, which dominates the pK a alk downshift towards physiological values. Electrostatic interactions, on the other hand, result in strong acceleration of the backward ligand exchange reaction, which dominates the pK a alk upshift. The different physicochemical conditions found here to influence pK a alk are expected to vary depending on cellular conditions and subcellular localization of the protein, thus determining the existence of alternative conformations of Cyt in vivo. © 2019 Elsevier Inc. |
| title |
The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| title_short |
The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| title_full |
The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| title_fullStr |
The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| title_full_unstemmed |
The alkaline transition of cytochrome c revisited: Effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| title_sort |
alkaline transition of cytochrome c revisited: effects of electrostatic interactions and tyrosine nitration on the reaction dynamics |
| publishDate |
2019 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00039861_v665_n_p96_OviedoRouco http://hdl.handle.net/20.500.12110/paper_00039861_v665_n_p96_OviedoRouco |
| _version_ |
1768544435841269760 |