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Dali A, Sebastiani F, Gabler T, Frattini G, Moreno DM, Estrin DA, Becucci M, Hofbauer S, Smulevich G. Proximal ligand tunes active site structure and reactivity in bacterial L. monocytogenes coproheme ferrochelatase. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 313:124120. [PMID: 38479228 DOI: 10.1016/j.saa.2024.124120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 02/21/2024] [Accepted: 03/03/2024] [Indexed: 04/02/2024]
Abstract
Ferrochelatases catalyze the insertion of ferrous iron into the porphyrin during the heme b biosynthesis pathway, which is fundamental for both prokaryotes and eukaryotes. Interestingly, in the active site of ferrochelatases, the proximal ligand coordinating the porphyrin iron of the product is not conserved, and its catalytic role is still unclear. Here we compare the L. monocytogenes bacterial coproporphyrin ferrochelatase native enzyme together with selected variants, where the proximal Tyr residue was replaced by a His (i.e. the most common ligand in heme proteins), a Met or a Phe (as in human and actinobacterial ferrochelatases, respectively), in their Fe(III), Fe(II) and Fe(II)-CO adduct forms. The study of the active site structure and the activity of the proteins in solution has been performed by UV-vis electronic absorption and resonance Raman spectroscopies, biochemical characterization, and classical MD simulations. All the mutations alter the H-bond interactions between the iron porphyrin propionate groups and the protein, and induce effects on the activity, depending on the polarity of the proximal ligand. The overall results confirm that the weak or non-existing coordination of the porphyrin iron by the proximal residue is essential for the binding of the substrate and the release of the final product.
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Affiliation(s)
- Andrea Dali
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Federico Sebastiani
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy
| | - Thomas Gabler
- University of Natural Resources and Life Sciences, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
| | - Gianfranco Frattini
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Diego M Moreno
- Instituto de Química Rosario (IQUIR, CONICET-UNR) and Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe, Argentina
| | - Darío A Estrin
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Universidad de Buenos Aires, Intendente Güiraldes, 2160 Buenos Aires, Argentina; CONICET - Universidad de Buenos Aires, Instituto de Química-Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Ciudad Universitaria, Pabellón 2, Buenos Aires, Argentina
| | - Maurizio Becucci
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy.
| | - Stefan Hofbauer
- University of Natural Resources and Life Sciences, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria.
| | - Giulietta Smulevich
- Dipartimento di Chimica "Ugo Schiff" (DICUS), Università di Firenze, Via della Lastruccia 3-13, I-50019 Sesto Fiorentino (FI), Italy; INSTM Research Unit of Firenze, via della Lastruccia 3, I-50019 Sesto Fiorentino, Italy.
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2
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Gabler T, Dali A, Bellei M, Sebastiani F, Becucci M, Battistuzzi G, Furtmüller PG, Smulevich G, Hofbauer S. Revisiting catalytic His and Glu residues in coproporphyrin ferrochelatase - unexpected activities of active site variants. FEBS J 2024. [PMID: 38390750 DOI: 10.1111/febs.17101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/17/2024] [Accepted: 02/13/2024] [Indexed: 02/24/2024]
Abstract
The identification of the coproporphyrin-dependent heme biosynthetic pathway, which is used almost exclusively by monoderm bacteria in 2015 by Dailey et al. triggered studies aimed at investigating the enzymes involved in this pathway that were originally assigned to the protoporphyrin-dependent heme biosynthetic pathway. Here, we revisit the active site of coproporphyrin ferrochelatase by a biophysical and biochemical investigation using the physiological substrate coproporphyrin III, which in contrast to the previously used substrate protoporphyrin IX has four propionate substituents and no vinyl groups. In particular, we have compared the reactivity of wild-type coproporphyrin ferrochelatase from the firmicute Listeria monocytogenes with those of variants, namely, His182Ala (H182A) and Glu263Gln (E263Q), involving two key active site residues. Interestingly, both variants are active only toward the physiological substrate coproporphyrin III but inactive toward protoporphyrin IX. In addition, E263 exchange impairs the final oxidation step from ferrous coproheme to ferric coproheme. The characteristics of the active site in the context of the residues involved and the substrate binding properties are discussed here using structural and functional means, providing a further contribution to the deciphering of this enigmatic reaction mechanism.
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Affiliation(s)
- Thomas Gabler
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Andrea Dali
- Department of Chemistry "Ugo Schiff" (DICUS), University of Florence, Sesto Fiorentino, Italy
| | - Marzia Bellei
- Department of Life Sciences, University of Modena and Reggio Emilia, Italy
| | - Federico Sebastiani
- Department of Chemistry "Ugo Schiff" (DICUS), University of Florence, Sesto Fiorentino, Italy
| | - Maurizio Becucci
- Department of Chemistry "Ugo Schiff" (DICUS), University of Florence, Sesto Fiorentino, Italy
| | - Gianantonio Battistuzzi
- Department of Chemical and Geological Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Paul Georg Furtmüller
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Giulietta Smulevich
- Department of Chemistry "Ugo Schiff" (DICUS), University of Florence, Sesto Fiorentino, Italy
- INSTM Research Unit of Firenze, Sesto Fiorentino, Italy
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
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Weaver BR, Perkins LJ, Fernandez Candelaria FO, Burstyn JN, Buller AR. Molecular Determinants of Efficient Cobalt-Substituted Hemoprotein Production in E. coli. ACS Synth Biol 2023; 12:3669-3679. [PMID: 37963151 DOI: 10.1021/acssynbio.3c00481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Exchanging the native iron of heme for other metals yields artificial metalloproteins with new properties for spectroscopic studies and biocatalysis. Recently, we reported a method for the biosynthesis and incorporation of a non-natural metallocofactor, cobalt protoporphyrin IX (CoPPIX), into hemoproteins using the common laboratory strain Escherichia coli BL21(DE3). This discovery inspired us to explore the determinants of metal specificity for metallocofactor biosynthesis in E. coli. Herein, we report detailed kinetic analysis of the ferrochelatase responsible for metal insertion, EcHemH (E. coli ferrochelatase). This enzyme exhibits a small, less than 2-fold preference for Fe2+ over the non-native Co2+ substrate in vitro. To test how mutations impact EcHemH, we used a surrogate metal specificity screen to identify variants with altered metal insertion preferences. This engineering process led to a variant with an ∼30-fold shift in specificity toward Co2+. When assayed in vivo, however, the impact of this mutation is small compared to the effects of alteration of the external metal concentrations. These data suggest that incorporation of cobalt into PPIX is enabled by the native promiscuity of EcHemH coupled with BL21's impaired ability to maintain transition-metal homeostasis. With this knowledge, we generated a method for CoPPIX production in rich media, which yields cobalt-substituted hemoproteins with >95% cofactor purity and yields comparable to standard expression protocols for the analogous native hemoproteins.
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Affiliation(s)
- Brian R Weaver
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Lydia J Perkins
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | | | - Judith N Burstyn
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Andrew R Buller
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
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Gabler T, Dali A, Sebastiani F, Furtmüller PG, Becucci M, Hofbauer S, Smulevich G. Iron insertion into coproporphyrin III-ferrochelatase complex: Evidence for an intermediate distorted catalytic species. Protein Sci 2023; 32:e4788. [PMID: 37743577 PMCID: PMC10578119 DOI: 10.1002/pro.4788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/07/2023] [Accepted: 09/20/2023] [Indexed: 09/26/2023]
Abstract
Understanding the reaction mechanism of enzymes at the molecular level is generally a difficult task, since many parameters affect the turnover. Often, due to high reactivity and formation of transient species or intermediates, detailed information on enzymatic catalysis is obtained by means of model substrates. Whenever possible, it is essential to confirm a reaction mechanism based on substrate analogues or model systems by using the physiological substrates. Here we disclose the ferrous iron incorporation mechanism, in solution, and in crystallo, by the coproporphyrin III-coproporphyrin ferrochelatase complex from the firmicute, pathogen, and antibiotic resistant, Listeria monocytogenes. Coproporphyrin ferrochelatase plays an important physiological role as the metalation represents the penultimate reaction step in the prokaryotic coproporphyrin-dependent heme biosynthetic pathway, yielding coproheme (ferric coproporphyrin III). By following the metal titration with resonance Raman spectroscopy and x-ray crystallography, we prove that upon metalation the saddling distortion becomes predominant both in the crystal and in solution. This is a consequence of the readjustment of hydrogen bond interactions of the propionates with the protein scaffold during the enzymatic catalysis. Once the propionates have established the interactions typical of the coproheme complex, the distortion slowly decreases, to reach the almost planar final product.
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Affiliation(s)
- Thomas Gabler
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Andrea Dali
- Dipartimento di Chimica “Ugo Schiff”—DICUSUniversità di FirenzeSesto FiorentinoItaly
| | - Federico Sebastiani
- Dipartimento di Chimica “Ugo Schiff”—DICUSUniversità di FirenzeSesto FiorentinoItaly
| | - Paul Georg Furtmüller
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Maurizio Becucci
- Dipartimento di Chimica “Ugo Schiff”—DICUSUniversità di FirenzeSesto FiorentinoItaly
| | - Stefan Hofbauer
- Department of ChemistryInstitute of Biochemistry, University of Natural Resources and Life SciencesViennaAustria
| | - Giulietta Smulevich
- Dipartimento di Chimica “Ugo Schiff”—DICUSUniversità di FirenzeSesto FiorentinoItaly
- INSTM Research Unit of FirenzeSesto FiorentinoItaly
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Falb N, Patil G, Furtmüller PG, Gabler T, Hofbauer S. Structural aspects of enzymes involved in prokaryotic Gram-positive heme biosynthesis. Comput Struct Biotechnol J 2023; 21:3933-3945. [PMID: 37593721 PMCID: PMC10427985 DOI: 10.1016/j.csbj.2023.07.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/19/2023] [Accepted: 07/19/2023] [Indexed: 08/19/2023] Open
Abstract
The coproporphyrin dependent heme biosynthesis pathway is almost exclusively utilized by Gram-positive bacteria. This fact makes it a worthwhile topic for basic research, since a fundamental understanding of a metabolic pathway is necessary to translate the focus towards medical biotechnology, which is very relevant in this specific case, considering the need for new antibiotic targets to counteract the pathogenicity of Gram-positive superbugs. Over the years a lot of structural data on the set of enzymes acting in Gram-positive heme biosynthesis has accumulated in the Protein Database (www.pdb.org). One major challenge is to filter and analyze all available structural information in sufficient detail in order to be helpful and to draw conclusions. Here we pursued to give a holistic overview of structural information on enzymes involved in the coproporphyrin dependent heme biosynthesis pathway. There are many aspects to be extracted from experimentally determined structures regarding the reaction mechanisms, where the smallest variation of the position of an amino acid residue might be important, but also on a larger level regarding protein-protein interactions, where the focus has to be on surface characteristics and subunit (secondary) structural elements and oligomerization. This review delivers a status quo, highlights still missing information, and formulates future research endeavors in order to better understand prokaryotic heme biosynthesis.
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Affiliation(s)
- Nikolaus Falb
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
| | - Gaurav Patil
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul G. Furtmüller
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
| | - Thomas Gabler
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
| | - Stefan Hofbauer
- University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Institute of Biochemistry, Muthgasse 18, A-1190 Vienna, Austria
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Hunter GA, Ferreira GC. Metal ion coordination sites in ferrochelatase. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Obi CD, Bhuiyan T, Dailey HA, Medlock AE. Ferrochelatase: Mapping the Intersection of Iron and Porphyrin Metabolism in the Mitochondria. Front Cell Dev Biol 2022; 10:894591. [PMID: 35646904 PMCID: PMC9133952 DOI: 10.3389/fcell.2022.894591] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 04/14/2022] [Indexed: 12/29/2022] Open
Abstract
Porphyrin and iron are ubiquitous and essential for sustaining life in virtually all living organisms. Unlike iron, which exists in many forms, porphyrin macrocycles are mostly functional as metal complexes. The iron-containing porphyrin, heme, serves as a prosthetic group in a wide array of metabolic pathways; including respiratory cytochromes, hemoglobin, cytochrome P450s, catalases, and other hemoproteins. Despite playing crucial roles in many biological processes, heme, iron, and porphyrin intermediates are potentially cytotoxic. Thus, the intersection of porphyrin and iron metabolism at heme synthesis, and intracellular trafficking of heme and its porphyrin precursors are tightly regulated processes. In this review, we discuss recent advances in understanding the physiological dynamics of eukaryotic ferrochelatase, a mitochondrially localized metalloenzyme. Ferrochelatase catalyzes the terminal step of heme biosynthesis, the insertion of ferrous iron into protoporphyrin IX to produce heme. In most eukaryotes, except plants, ferrochelatase is localized to the mitochondrial matrix, where substrates are delivered and heme is synthesized for trafficking to multiple cellular locales. Herein, we delve into the structural and functional features of ferrochelatase, as well as its metabolic regulation in the mitochondria. We discuss the regulation of ferrochelatase via post-translational modifications, transportation of substrates and product across the mitochondrial membrane, protein-protein interactions, inhibition by small-molecule inhibitors, and ferrochelatase in protozoal parasites. Overall, this review presents insight on mitochondrial heme homeostasis from the perspective of ferrochelatase.
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Affiliation(s)
- Chibuike David Obi
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
| | - Tawhid Bhuiyan
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
| | - Harry A. Dailey
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- Department of Microbiology, University of Georgia, Athens, GA, United States
| | - Amy E. Medlock
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United States
- Augusta University/University of Georgia Medical Partnership, University of Georgia, Athens, GA, United States
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Iron, Heme Synthesis and Erythropoietic Porphyrias: A Complex Interplay. Metabolites 2021; 11:metabo11120798. [PMID: 34940556 PMCID: PMC8705723 DOI: 10.3390/metabo11120798] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 12/13/2022] Open
Abstract
Erythropoietic porphyrias are caused by enzymatic dysfunctions in the heme biosynthetic pathway, resulting in porphyrins accumulation in red blood cells. The porphyrins deposition in tissues, including the skin, leads to photosensitivity that is present in all erythropoietic porphyrias. In the bone marrow, heme synthesis is mainly controlled by intracellular labile iron by post-transcriptional regulation: translation of ALAS2 mRNA, the first and rate-limiting enzyme of the pathway, is inhibited when iron availability is low. Moreover, it has been shown that the expression of ferrochelatase (FECH, an iron-sulfur cluster enzyme that inserts iron into protoporphyrin IX to form heme), is regulated by intracellular iron level. Accordingly, there is accumulating evidence that iron status can mitigate disease expression in patients with erythropoietic porphyrias. This article will review the available clinical data on how iron status can modify the symptoms of erythropoietic porphyrias. We will then review the modulation of heme biosynthesis pathway by iron availability in the erythron and its role in erythropoietic porphyrias physiopathology. Finally, we will summarize what is known of FECH interactions with other proteins involved in iron metabolism in the mitochondria.
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Gabler T, Sebastiani F, Helm J, Dali A, Obinger C, Furtmüller PG, Smulevich G, Hofbauer S. Substrate specificity and complex stability of coproporphyrin ferrochelatase is governed by hydrogen-bonding interactions of the four propionate groups. FEBS J 2021; 289:1680-1699. [PMID: 34719106 DOI: 10.1111/febs.16257] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/19/2021] [Accepted: 10/28/2021] [Indexed: 11/24/2022]
Abstract
Coproporpyhrin III is the substrate of coproporphyrin ferrochelatases (CpfCs). These enzymes catalyse the insertion of ferrous iron into the porphyrin ring. This is the penultimate step within the coproporphyrin-dependent haeme biosynthesis pathway. This pathway was discovered in 2015 and is mainly utilised by monoderm bacteria. Prior to this discovery, monoderm bacteria were believed to utilise the protoporphyrin-dependent pathway, analogously to diderm bacteria, where the substrate for the respective ferrochelatase is protoporphyrin IX, which has two propionate groups at positions 6 and 7 and two vinyl groups at positions 2 and 4. In this work, we describe for the first time the interactions of the four-propionate substrate, coproporphyrin III, and the four-propionate product, iron coproporphyrin III (coproheme), with the CpfC from Listeria monocytogenes and pin down differences with respect to the protoporphyrin IX and haeme b complexes in the wild-type (WT) enzyme. We further created seven LmCpfC variants aiming at altering substrate and product coordination. The WT enzyme and all the variants were comparatively studied by spectroscopic, thermodynamic and kinetic means to investigate in detail the H-bonding interactions, which govern complex stability and substrate specificity. We identified a tyrosine residue (Y124 in LmCpfC), coordinating the propionate at position 2, which is conserved in monoderm CpfCs, to be highly important for binding and stabilisation. Importantly, we also describe a tyrosine-serine-threonine triad, which coordinates the propionate at position 4. The study of the triad variants indicates structural differences between the coproporphyrin III and the coproheme complexes. ENZYME: EC 4.99.1.9.
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Affiliation(s)
- Thomas Gabler
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Federico Sebastiani
- Dipartimento di Chimica 'Ugo Schiff' (DICUS), Università di Firenze, Sesto Fiorentino, Italy
| | - Johannes Helm
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Andrea Dali
- Dipartimento di Chimica 'Ugo Schiff' (DICUS), Università di Firenze, Sesto Fiorentino, Italy
| | - Christian Obinger
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Paul G Furtmüller
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Giulietta Smulevich
- Dipartimento di Chimica 'Ugo Schiff' (DICUS), Università di Firenze, Sesto Fiorentino, Italy.,INSTM Research Unit of Firenze, Sesto Fiorentino, Italy
| | - Stefan Hofbauer
- Department of Chemistry, Institute of Biochemistry, University of Natural Resources and Life Sciences, Vienna, Austria
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