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Nelson Z, Delage-Laurin L, Swager TM. ABCs of Faraday Rotation in Organic Materials. J Am Chem Soc 2022; 144:11912-11926. [PMID: 35762922 DOI: 10.1021/jacs.2c01983] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Faraday rotation is a magneto-optical effect central to a number of commercial technologies including optical isolation and magneto-optical imaging. Today, the performance needs of these technologies are met by inorganic materials containing paramagnetic heavy elements. However, organic thin films are increasingly being evaluated as replacement materials, promising higher magneto-optical performance and facile fabrication of structures that enable expanded applications. Despite being an object of research for more than 175 years, our understanding of the Faraday effect in solid-state organic materials remains incomplete, hindering our attempts to methodically improve magneto-optical performance. This Perspective aims to place several recent advances in the field of thin-film organic Faraday rotators within the well-established theoretical framework developed by solution-state magnetic circular dichroism spectroscopists: the Faraday A, B, and C terms. Through careful consideration of these quantum mechanical mechanisms in example molecules, an intuitive understanding of the impact of chemical structure in thin-film Faraday rotators can be achieved, including the critical roles of molecular symmetry, rigidity, absorptivity, and magnetism. Future work seeking to maximize the magneto-optical performance of organic thin films may more readily evaluate candidate chromophores based on the Faraday A, B, and C term framework presented herein.
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Affiliation(s)
- Zachary Nelson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Léo Delage-Laurin
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Timothy M Swager
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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2
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Patel AY, Jonnalagadda KS, Paradis N, Vaden TD, Wu C, Caputo GA. Effects of Ionic Liquids on Metalloproteins. Molecules 2021; 26:514. [PMID: 33478102 PMCID: PMC7835893 DOI: 10.3390/molecules26020514] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/04/2021] [Accepted: 01/08/2021] [Indexed: 01/28/2023] Open
Abstract
In the past decade, innovative protein therapies and bio-similar industries have grown rapidly. Additionally, ionic liquids (ILs) have been an area of great interest and rapid development in industrial processes over a similar timeline. Therefore, there is a pressing need to understand the structure and function of proteins in novel environments with ILs. Understanding the short-term and long-term stability of protein molecules in IL formulations will be key to using ILs for protein technologies. Similarly, ILs have been investigated as part of therapeutic delivery systems and implicated in numerous studies in which ILs impact the activity and/or stability of protein molecules. Notably, many of the proteins used in industrial applications are involved in redox chemistry, and thus often contain metal ions or metal-associated cofactors. In this review article, we focus on the current understanding of protein structure-function relationship in the presence of ILs, specifically focusing on the effect of ILs on metal containing proteins.
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Affiliation(s)
- Aashka Y. Patel
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA; (A.Y.P.); (N.P.); (T.D.V.); (C.W.)
| | | | - Nicholas Paradis
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA; (A.Y.P.); (N.P.); (T.D.V.); (C.W.)
| | - Timothy D. Vaden
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA; (A.Y.P.); (N.P.); (T.D.V.); (C.W.)
| | - Chun Wu
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA; (A.Y.P.); (N.P.); (T.D.V.); (C.W.)
- Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, NJ 08028, USA
| | - Gregory A. Caputo
- Department of Chemistry and Biochemistry, Rowan University, Glassboro, NJ 08028, USA; (A.Y.P.); (N.P.); (T.D.V.); (C.W.)
- Department of Molecular and Cellular Biosciences, Rowan University, Glassboro, NJ 08028, USA
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3
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Han B, Gao X, Lv J, Tang Z. Magnetic Circular Dichroism in Nanomaterials: New Opportunity in Understanding and Modulation of Excitonic and Plasmonic Resonances. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1801491. [PMID: 30345582 DOI: 10.1002/adma.201801491] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 08/16/2018] [Indexed: 06/08/2023]
Abstract
The unique capability of magnetic circular dichroism (MCD) in revealing geometry and electronic information has provided new opportunities in exploring the relationship between structure and magneto-optical properties in nanomaterials with extraordinary optical absorption. Here, the representative studies referring to application of the MCD technique in semiconductor and noble metal nanomaterials are overviewed. MCD is powerful in elucidating the structural information of the excitonic transition in semiconductor nanocrystals, electronic transitions in noble metal nanoclusters, and plasmon resonance in noble metal nanostructures. By virtue of these advantages, the MCD technique shows its unrivalled ability in evaluating the magnetic modulation of excitonic and plasmonic optical activity of nanomaterials with varied chemical composition, geometry, assembly conformation, and coupling effect. Knowledge of the key factors in manipulating magneto-optical properties at the nanoscale acquired with the MCD technique will largely boost the application of semiconductor and noble nanomaterials in the fields of sensing, spintronic, nanophotonics, etc.
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Affiliation(s)
- Bing Han
- CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China
| | - Xiaoqing Gao
- College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, P. R. China
| | - Jiawei Lv
- College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, P. R. China
| | - Zhiyong Tang
- College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, P. R. China
- School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China
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4
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Evans LS, Hussain R, Siligardi G, Williamson PT. Magnetically aligned membrane mimetics enabling comparable chiroptical and magnetic resonance spectroscopy studies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183343. [DOI: 10.1016/j.bbamem.2020.183343] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 10/24/2022]
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5
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Paradisi A, Bellei M, Paltrinieri L, Bortolotti CA, Di Rocco G, Ranieri A, Borsari M, Sola M, Battistuzzi G. Binding of S. cerevisiae iso-1 cytochrome c and its surface lysine-to-alanine variants to cardiolipin: charge effects and the role of the lipid to protein ratio. J Biol Inorg Chem 2020; 25:467-487. [DOI: 10.1007/s00775-020-01776-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 03/06/2020] [Indexed: 11/30/2022]
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6
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Extraction of magnetic circular dichroism effects from blended mixture of magnetic linear dichroism signals in the cobalt/Scotch tape system. Sci Rep 2019; 9:17192. [PMID: 31748587 PMCID: PMC6868135 DOI: 10.1038/s41598-019-53880-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 11/06/2019] [Indexed: 01/23/2023] Open
Abstract
Circular dichroism (CD) signals revealed in some materials may arise from different origins during measurements. Magnetic field dependent CD (MCD) emanating from the spin-polarized band provides direct insight into the spin-spin interband transitions in magnetic materials. On the contrary, natural CD effects which are artefactual signals resulting from the linear polarization (LP) components during the polarization modulation with a photo-elastic modulator in anisotropic polymer systems were usually observed. There is no simple method to reliably distinguish MCD effect due to spin polarized band structures from natural CD effect, which limits our understanding of the magnetic material/polymer hybrid structures. This paper aims to introduce a general strategy of averaging out the magnetic linear dichroism (MLD) contributions due to the anisotropic structure and disentangling MCD signal(s) from natural MCD signal(s). We demonstrate the effectiveness of separating MCD from natural MCD using rotational MCD measurement and presented the results of a sample with Co thin film on polymer Scotch tape (unplasticized polyvinyl chloride) glued on a quartz substrate. We demonstrate that the proposed method can be used as an effective tool in disentangling MCD and natural MCD effects, and it opens prospects to study the magnetic material /polymer hybrid systems.
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7
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Manesis AC, Musselman BW, Keegan BC, Shearer J, Lehnert N, Shafaat HS. A Biochemical Nickel(I) State Supports Nucleophilic Alkyl Addition: A Roadmap for Methyl Reactivity in Acetyl Coenzyme A Synthase. Inorg Chem 2019; 58:8969-8982. [PMID: 30788970 PMCID: PMC6635881 DOI: 10.1021/acs.inorgchem.8b03546] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
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Nickel-containing
enzymes such as methyl coenzyme M reductase (MCR) and carbon monoxide
dehydrogenase/acetyl coenzyme A synthase (CODH/ACS) play a critical
role in global energy conversion reactions, with significant contributions
to carbon-centered processes. These enzymes are implied to cycle through
a series of nickel-based organometallic intermediates during catalysis,
though identification of these intermediates remains challenging.
In this work, we have developed and characterized a nickel-containing
metalloprotein that models the methyl-bound organometallic intermediates
proposed in the native enzymes. Using a nickel(I)-substituted azurin
mutant, we demonstrate that alkyl binding occurs via nucleophilic
addition of methyl iodide as a methyl donor. The paramagnetic NiIII-CH3 species initially generated can be rapidly
reduced to a high-spin NiII-CH3 species in the
presence of exogenous reducing agent, following a reaction sequence
analogous to that proposed for ACS. These two distinct bioorganometallic
species have been characterized by optical, EPR, XAS, and MCD spectroscopy,
and the overall mechanism describing methyl reactivity with nickel
azurin has been quantitatively modeled using global kinetic simulations.
A comparison between the nickel azurin protein system and existing
ACS model compounds is presented. NiIII-CH3 Az
is only the second example of two-electron addition of methyl iodide
to a NiI center to give an isolable species and the first
to be formed in a biologically relevant system. These results highlight
the divergent reactivity of nickel across the two intermediates, with
implications for likely reaction mechanisms and catalytically relevant
states in the native ACS enzyme. A bioorganometallic model
for acetyl coenzyme A synthase has been developed. This model protein
is able to bind a cationic methyl group via direct addition to the
nickel(I) center. The resultant nickel(III)-methyl species has been
characterized via optical and electron paramagnetic resonance spectroscopy,
and the reduced nickel(II)-methyl state has been characterized using
magnetic circular dichroism and X-ray spectroscopy. Implications for
further reactivity with CO are gleaned from electronic structure analysis
of the nickel-methyl species.
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Affiliation(s)
- Anastasia C Manesis
- Department of Chemistry and Biochemistry , The Ohio State University , 100 W. 18th Avenue , Columbus , Ohio 43210 , United States
| | - Bradley W Musselman
- Department of Chemistry , University of Michigan , 930 N. University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Brenna C Keegan
- Department of Chemistry , Trinity University , One Trinity Place , San Antonio , Texas 78212 , United States
| | - Jason Shearer
- Department of Chemistry , Trinity University , One Trinity Place , San Antonio , Texas 78212 , United States
| | - Nicolai Lehnert
- Department of Chemistry , University of Michigan , 930 N. University Avenue , Ann Arbor , Michigan 48109 , United States
| | - Hannah S Shafaat
- Department of Chemistry and Biochemistry , The Ohio State University , 100 W. 18th Avenue , Columbus , Ohio 43210 , United States
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8
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Carpenter SH, Neidig ML. A Physical-Inorganic Approach for the Elucidation of Active Iron Species and Mechanism in Iron-Catalyzed Cross-Coupling. Isr J Chem 2017; 57:1106-1116. [PMID: 29622838 DOI: 10.1002/ijch.201700036] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Detailed studies of iron speciation and mechanism in iron-catalyzed cross-coupling reactions are critical for providing the necessary fundamental insight to drive new reaction development. However, such insight is challenging to obtain due to the prevalence of mixtures of unstable, paramagnetic organoiron species that can form in this chemistry. A physical-inorganic research approach combining freeze-trapped inorganic spectroscopic studies, organometallic synthesis and GC/kinetic studies provides a powerful method for studying such systems. Mössbauer, EPR and MCD spectroscopy enable the direct investigation of in situ formed iron species and, combined with GC analysis, the direct correlation of reactions of specific iron species to the generation of organic products. This review focuses on a description of the key methods involved in this physical-inorganic approach, as well as examples of its application to investigations of iron-SciOPP catalyzed cross-coupling catalysis.
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Affiliation(s)
- Stephanie H Carpenter
- Department of Chemistry, University of Rochester, Rochester, New York 14627 (USA), Tel: 585-276-6006
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627 (USA), Tel: 585-276-6006
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9
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Contrasting catalytic profiles of multiheme nitrite reductases containing CxxCK heme-binding motifs. J Biol Inorg Chem 2013; 18:655-67. [DOI: 10.1007/s00775-013-1011-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 06/01/2013] [Indexed: 10/26/2022]
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10
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Yamada M, Slanina Z, Mizorogi N, Muranaka A, Maeda Y, Nagase S, Akasaka T, Kobayashi N. Application of MCD spectroscopy and TD-DFT to endohedral metallofullerenes for characterization of their electronic transitions. Phys Chem Chem Phys 2013; 15:3593-601. [PMID: 23381223 DOI: 10.1039/c3cp44096f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe, for the first time, the application of magnetic circular dichroism (MCD) spectroscopy and time-dependent density functional theory (TD-DFT) calculations using B3LYP and M06-2X functionals to characterize the electronic transitions of endohedral metallofullerenes (EMFs). Results revealed that the electronic transitions of La@C(2v)-C(82), La(2)@I(h)-C(80), and Sc(3)N@I(h)-C(80) can be assigned using these techniques. Particularly, a difference in the electronic transitions between La(2)@I(h)-C(80) and Sc(3)N@I(h)-C(80), which is invisible in absorption spectra, was observed clearly in MCD spectra. The observed MCD bands agree well with the oscillator strengths calculated using the B3LYP functional. In addition, the MCD bands of La(2)@I(h)-C(80) were altered upon [5,6]-addition, demonstrating that the MCD spectroscopy is sensitive to chemical functionalization of EMFs, and that it is therefore powerful to distinguish [5,6]-adducts from pristine La(2)@I(h)-C(80), although no marked difference exists in their absorption spectra.
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Affiliation(s)
- Michio Yamada
- Department of Chemistry, Tokyo Gakugei University, Koganei, Tokyo, Japan.
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11
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Rose MJ, Bellone DE, Di Bilio AJ, Gray HB. Spectroscopic and magnetic properties of an iodo Co(I) tripodal phosphine complex. Dalton Trans 2012; 41:11788-97. [PMID: 22903546 DOI: 10.1039/c2dt31229h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction of the tripodal phosphine ligand 1,1,1-tris((diphenylphosphino)phenyl)ethane (PhP3) with CoI(2) spontaneously generates a one-electron reduced complex, [(PhP3)Co(I)(I)] (1). The crystal structure of 1 reveals a distorted tetrahedral environment, with an apical Co-I bond distance of ~2.52 Å. Co(II/I) redox occurs at an unusually high potential (+0.38 V vs. SCE). The electronic absorption spectrum of 1 exhibits an MLCT peak at 320 nm (ε = 8790 M(-1) cm(-1)) and a d-d feature at 850 nm (ε = 840 M(-1) cm(-1)). Two more d-d bands are observed in the NIR region, 8650 (ε = 450) and 7950 cm(-1) (ε = 430 M(-1) cm(-1)). Temperature dependent magnetic measurements (SQUID) on 1 (solid state, 20-300 K) give μ(eff) = 2.99(6) μ(B), consistent with an S = 1 ground state. Magnetic susceptibilities below 20 K are consistent with a zero field splitting (zfs) |D| = 8 cm(-1). DFT calculations also support a spin-triplet ground state for 1, as optimized (6-31G*/PW91) geometries (S = 1) closely match the X-ray structure. EPR measurements performed in parallel mode (X-band; 0-15,000 G, 15 K) on polycrystalline 1 or frozen solutions of 1 (THF/toluene) exhibit a feature at g≈ 4 that arises from a (Δm = 2) transition within the M(S) = <+1,-1> manifold. Below 10 K, the EPR signal decreases significantly, consistent with a solution zfs parameter (|D|≈ 8 cm(-1)) similar to that obtained from SQUID measurements. Our work provides an EPR signature for high-spin Co(I) in trigonal ligation.
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Affiliation(s)
- Michael J Rose
- Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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12
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Battistuzzi G, Bortolotti CA, Bellei M, Di Rocco G, Salewski J, Hildebrandt P, Sola M. Role of Met80 and Tyr67 in the Low-pH Conformational Equilibria of Cytochrome c. Biochemistry 2012; 51:5967-78. [DOI: 10.1021/bi3007302] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gianantonio Battistuzzi
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Carlo Augusto Bortolotti
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Marzia Bellei
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Giulia Di Rocco
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
| | - Johannes Salewski
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Peter Hildebrandt
- Technische Universität Berlin, Institut für Chemie, Sekr. PC14, Straße
des 17. Juni 135, D-10623 Berlin, Germany
| | - Marco Sola
- Department
of Chemistry, University of Modena and Reggio Emilia, via Campi 183,
41100 Modena, Italy
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13
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Solti A, Kovács K, Basa B, Vértes A, Sárvári E, Fodor F. Uptake and incorporation of iron in sugar beet chloroplasts. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2012; 52:91-7. [PMID: 22305071 DOI: 10.1016/j.plaphy.2011.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 11/29/2011] [Indexed: 05/24/2023]
Abstract
Chloroplasts contain 80-90% of iron taken up by plant cells. Though some iron transport-related envelope proteins were identified recently, the mechanism of iron uptake into chloroplasts remained unresolved. To shed more light on the process of chloroplast iron uptake, trials were performed with isolated intact chloroplasts of sugar beet (Beta vulgaris). Iron uptake was followed by measuring the iron content of chloroplasts in the form of ferrous-bathophenantroline-disulphonate complex after solubilising the chloroplasts in reducing environment. Ferric citrate was preferred to ferrous citrate as substrate for chloroplasts. Strong dependency of ferric citrate uptake on photosynthetic electron transport activity suggests that ferric chelate reductase uses NADPH, and is localised in the inner envelope membrane. The K(m) for iron uptake from ferric-citrate pool was 14.65 ± 3.13 μM Fe((III))-citrate. The relatively fast incorporation of (57)Fe isotope into Fe-S clusters/heme, detected by Mössbauer spectroscopy, showed the efficiency of the biosynthetic machinery of these cofactors in isolated chloroplasts. The negative correlation between the chloroplast iron concentration and the rate of iron uptake refers to a strong feedback regulation of the uptake.
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Affiliation(s)
- Adám Solti
- Department of Plant Physiology and Molecular Plant Biology, Institute of Biology, Eötvös Loránd University, Pázmány P. lane 1/C, Budapest 1117, Hungary
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14
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Yannone SM, Hartung S, Menon AL, Adams MWW, Tainer JA. Metals in biology: defining metalloproteomes. Curr Opin Biotechnol 2011; 23:89-95. [PMID: 22138493 DOI: 10.1016/j.copbio.2011.11.005] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 11/02/2011] [Accepted: 11/05/2011] [Indexed: 11/28/2022]
Abstract
The vital nature of metal uptake and balance in biology is evident in the highly evolved strategies to facilitate metal homeostasis in all three domains of life. Several decades of study on metals and metalloproteins have revealed numerous essential bio-metal functions. Recent advances in mass spectrometry, X-ray scattering/absorption, and proteomics have exposed a much broader usage of metals in biology than expected. Even elements such as uranium, arsenic, and lead are implicated in biological processes as part of an emerging and expansive view of bio-metals. Here we discuss opportunities and challenges for established and newer approaches to study metalloproteins with a focus on technologies that promise to rapidly expand our knowledge of metalloproteins and metal functions in biology.
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Affiliation(s)
- Steven M Yannone
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States.
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15
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Luthra A, Denisov IG, Sligar SG. Spectroscopic features of cytochrome P450 reaction intermediates. Arch Biochem Biophys 2010; 507:26-35. [PMID: 21167809 DOI: 10.1016/j.abb.2010.12.008] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 12/06/2010] [Accepted: 12/07/2010] [Indexed: 11/24/2022]
Abstract
Cytochromes P450 constitute a broad class of heme monooxygenase enzymes with more than 11,500 isozymes which have been identified in organisms from all biological kingdoms [1]. These enzymes are responsible for catalyzing dozens chemical oxidative transformations such as hydroxylation, epoxidation, N-demethylation, etc., with very broad range of substrates [2,3]. Historically these enzymes received their name from 'pigment 450' due to the unusual position of the Soret band in UV-vis absorption spectra of the reduced CO-saturated state [4,5]. Despite detailed biochemical characterization of many isozymes, as well as later discoveries of other 'P450-like heme enzymes' such as nitric oxide synthase and chloroperoxidase, the phenomenological term 'cytochrome P450' is still commonly used as indicating an essential spectroscopic feature of the functionally active protein which is now known to be due to the presence of a thiolate ligand to the heme iron [6]. Heme proteins with an imidazole ligand such as myoglobin and hemoglobin as well as an inactive form of P450 are characterized by Soret maxima at 420nm [7]. This historical perspective highlights the importance of spectroscopic methods for biochemical studies in general, and especially for heme enzymes, where the presence of the heme iron and porphyrin macrocycle provides rich variety of specific spectroscopic markers available for monitoring chemical transformations and transitions between active intermediates of catalytic cycle.
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Affiliation(s)
- Abhinav Luthra
- Department of Biochemistry, School of Molecular and Cellular Biology, University of Illinois, Urbana, IL 61801, USA
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