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Abstract
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Thanks to recent
improvements in NMR spectrometer hardware and
pulse sequence design, modern 13C NMR has become a useful
tool for biomolecular applications. The complete assignment of a protein
can be accomplished by using 13C detected multinuclear
experiments and it can provide unique information relevant for the
study of a variety of different biomolecules including paramagnetic
proteins and intrinsically disordered proteins. A wide range of NMR
observables can be measured, concurring to the structural and dynamic
characterization of a protein in isolation, as part of a larger complex,
or even inside a living cell. We present the different properties
of 13C with respect to 1H, which provide the
rationale for the experiments developed and their application, the
technical aspects that need to be faced, and the many experimental
variants designed to address different cases. Application areas where
these experiments successfully complement proton NMR are also described.
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Affiliation(s)
- Isabella C Felli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Roberta Pierattelli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
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Lalli D, Rosa C, Allegrozzi M, Turano P. Distal Unfolding of Ferricytochrome c Induced by the F82K Mutation. Int J Mol Sci 2020; 21:ijms21062134. [PMID: 32244917 PMCID: PMC7139943 DOI: 10.3390/ijms21062134] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 01/03/2023] Open
Abstract
It is well known that axial coordination of heme iron in mitochondrial cytochrome c has redox-dependent stability. The Met80 heme iron axial ligand in the ferric form of the protein is relatively labile and can be easily replaced by alternative amino acid side chains under non-native conditions induced by alkaline pH, high temperature, or denaturing agents. Here, we showed a redox-dependent destabilization induced in human cytochrome c by substituting Phe82-conserved amino acid and a key actor in cytochrome c intermolecular interactions-with a Lys residue. Introducing a positive charge at position 82 did not significantly affect the structure of ferrous cytochrome c but caused localized unfolding of the distal site in the ferric state. As revealed by 1H NMR fingerprint, the ferric form of the F82K variant had axial coordination resembling the renowned alkaline species, where the detachment of the native Met80 ligand favored the formation of multiple conformations involving distal Lys residues binding to iron, but with more limited overall structural destabilization.
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Affiliation(s)
- Daniela Lalli
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; (D.L.); (C.R.); (M.A.)
- Present Address: Dipartimento di Scienze e Innovazione Tecnologica, Università del Piemonte Orientale “A. Avogadro”, Viale T. Michel 11, 15121 Alessandria, Italy
| | - Camilla Rosa
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; (D.L.); (C.R.); (M.A.)
| | - Marco Allegrozzi
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; (D.L.); (C.R.); (M.A.)
| | - Paola Turano
- Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino, Florence, Italy; (D.L.); (C.R.); (M.A.)
- Correspondence: ; Tel.: +39-055-457-4266
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About the use of 13C- 13C NOESY in bioinorganic chemistry. J Inorg Biochem 2018; 192:25-32. [PMID: 30562672 DOI: 10.1016/j.jinorgbio.2018.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/07/2018] [Accepted: 12/08/2018] [Indexed: 10/27/2022]
Abstract
Herein we present examples of the application of the 13C-13C Nuclear Overhauser Effect Spectroscopy (NOESY) experiment to the study of metalloproteins and we critically discuss the advantages and drawbacks of the method as a function of the molecular size of the investigated systems. The contribution is focused on a few case studies among the systems analyzed in the group of the corresponding author. The 13C-13C NOESY experiment represents the gold standard for the observation of NMR signals in the 480 kDa ferritin nanocage and for monitoring its interaction with iron. By decreasing the protein size, the experiment progressively loses its importance as a tool for the detection of the complete spin pattern of the amino acid side chains, as exemplified by nickel-dependent regulatory protein, NikR (molecular mass of the homo-tetramer ~80 kDa). In very small proteins, such as mitochondrial cytochrome c (12.3 kDa), we are only able to detect cross peaks between adjacent 13C nuclei; this feature turned out to be useful for the assignment of the 13C core resonances of the porphyrin in a uniformly enriched heme.
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Feifel SC, Stieger KR, Kapp A, Weber D, Allegrozzi M, Piccioli M, Turano P, Lisdat F. Insights into Interprotein Electron Transfer of Human Cytochrome c Variants Arranged in Multilayer Architectures by Means of an Artificial Silica Nanoparticle Matrix. ACS OMEGA 2016; 1:1058-1066. [PMID: 30023500 PMCID: PMC6044710 DOI: 10.1021/acsomega.6b00213] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/04/2016] [Indexed: 06/08/2023]
Abstract
The redox behavior of proteins plays a crucial part in the design of bioelectronic systems. We have demonstrated several functional systems exploiting the electron exchange properties of the redox protein cytochrome c (cyt c) in combination with enzymes and photoactive proteins. The operation is based on an effective reaction at modified electrodes but also to a large extent on the capability of self-exchange between cyt c molecules in a surface-fixed state. In this context, different variants of human cyt c have been examined here with respect to an altered heterogeneous electron transfer (ET) rate in a monolayer on electrodes as well as an enhanced self-exchange rate while being incorporated in multilayer architectures. For this purpose, mutants of the wild-type (WT) protein have been prepared to change the chemical nature of the surface contact area near the heme edge. The structural integrity of the variants has been verified by NMR and UV-vis measurements. It is shown that the single-point mutations can significantly influence the heterogeneous ET rate at thiol-modified gold electrodes and that electroactive protein/silica nanoparticle multilayers can be constructed with all forms of human cyt c prepared. The kinetic behavior of electron exchange for the mutant proteins in comparison with that of the WT has been found altered in some multilayer arrangements. Higher self-exchange rates have been found for K79A. The results demonstrate that the position of the introduced change in the charge situation of cyt c has a profound influence on the exchange behavior. In addition, the behavior of the cyt c variants in assembled multilayers is found to be rather similar to the situation of cyt c self-exchange in solution verified by NMR.
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Affiliation(s)
- Sven Christian Feifel
- Institute
of Applied Life Sciences, Biosystems Technology, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Kai Ralf Stieger
- Institute
of Applied Life Sciences, Biosystems Technology, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Andreas Kapp
- Institute
of Applied Life Sciences, Biosystems Technology, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Dennis Weber
- Institute
of Applied Life Sciences, Biosystems Technology, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
| | - Marco Allegrozzi
- Department
of Chemistry and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 2, 50019 Sesto Fiorentino, Florence, Italy
| | - Mario Piccioli
- Department
of Chemistry and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 2, 50019 Sesto Fiorentino, Florence, Italy
| | - Paola Turano
- Department
of Chemistry and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 2, 50019 Sesto Fiorentino, Florence, Italy
| | - Fred Lisdat
- Institute
of Applied Life Sciences, Biosystems Technology, Technical University of Applied Sciences Wildau, Hochschulring 1, 15745 Wildau, Germany
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