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Lucas HR. Special issue in memory of Jim Terner: Celebrating his career and contributions to physical inorganic biochemistry. J Inorg Biochem 2023:112265. [PMID: 37258306 DOI: 10.1016/j.jinorgbio.2023.112265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, USA.
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2
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Lucas HR. Honoring James Terner - Celebrating his career and contributions to physical inorganic biochemistry. J Inorg Biochem 2023:112262. [PMID: 37263886 DOI: 10.1016/j.jinorgbio.2023.112262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, United States.
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3
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Lucas HR, Kim E, Ghiladi RA. Celebrating Kenneth D. Karlin for his ACS Award for Distinguished Service in the Advancement of Inorganic Chemistry. J Inorg Biochem 2023; 241:112142. [PMID: 36804183 DOI: 10.1016/j.jinorgbio.2023.112142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, United States.
| | - Eunsuk Kim
- Department of Chemistry, Brown University, United States.
| | - Reza A Ghiladi
- Department of Chemistry, North Carolina State University, United States.
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4
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Lucas HR, Kim E, Ghiladi RA. Journal of Inorganic Biochemistry - Karlin Special Issue. J Inorg Biochem 2023; 241:112143. [PMID: 36740483 DOI: 10.1016/j.jinorgbio.2023.112143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, United States.
| | - Eunsuk Kim
- Department of Chemistry, Brown University, United States.
| | - Reza A Ghiladi
- Department of Chemistry, North Carolina State University, United States.
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Khamespanah F, Patel NM, Forney AK, Heitger DR, Amarasekarage CM, Springer LE, Belecki K, Lucas HR. Flavonol dioxygenase chemistry mediated by a synthetic nickel superoxide. J Inorg Biochem 2023; 238:112021. [PMID: 36395718 DOI: 10.1016/j.jinorgbio.2022.112021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 10/01/2022] [Accepted: 10/02/2022] [Indexed: 11/16/2022]
Abstract
Nature exploits transition metal centers to enhance and tune the oxidizing power of natural oxidants such as O2 and H2O2. The design and interrogation of synthetic metallocomplexes with similar reactivity to metalloproteins provides one strategy for gaining insight into the mechanistic underpinnings of oxygen-activating enzymes such as oxidases, oxygenases, and dioxygenases like Ni-quercetinase (Ni-QueD). Ni-QueD catalyzes the oxidative ring opening of the polyphenol quercetin, a natural product with antioxidant properties. Herein, we report the synthesis and characterization of Ni(13-DOB), a Ni(II) species complexed by an N4-macrocycle that has been characterized by single crystal X-ray crystallography. Ni(13-DOB) forms a Ni-superoxide intermediate (Ni(13-DOB)O2•-) upon treatment with H2O2 and Et3N, as verified by resonance Raman spectroscopy. We demonstrate through UV/vis and LCMS that Ni(13-DOB)O2•- is capable of the 1-electron oxidation of flavonols, including both 3-hydroxyflavone (3-HF, the simplest flavonol) and quercetin itself. Incorporation of two O-atoms into the flavonol radical via superoxide from Ni(13-DOB)O2•- precedes oxidative cleavage of the flavonol scaffold in each case, consistent with quercetinase ring cleavage by Ni-QueD in Streptomyces sp. FLA. Conversion of 3-HF into 2-hydroxybenzoylbenzoic acid was accomplished with catalytic turnover of Ni(13-DOB) at ambient temperature, as confirmed by HPLC timecourses and GCMS analysis of isotopic labeling studies. The Ni(13-DOB)-mediated oxidative cleavage of quercetin to the corresponding biomimetic phenolic ester was also verified through 18O-isotopic labeling studies. Through the HPLC characterization of both on- and off-pathway products of flavonol dioxygenation by Ni(13-DOB)O2•-, the stringent reaction pathway control provided by enzyme active sites is highlighted.
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Affiliation(s)
- F Khamespanah
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - N M Patel
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - A K Forney
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - D R Heitger
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - C M Amarasekarage
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - L E Springer
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America
| | - K Belecki
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America.
| | - H R Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA 23284, United States of America.
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Curry AM, Fernàndez RD, Pagani TD, Abeyawardhane DL, Trahan ML, Lucas HR. Mapping of Photochemically-Derived Dityrosine across Fe-Bound N-Acetylated α-Synuclein. Life (Basel) 2020; 10:life10080124. [PMID: 32726960 PMCID: PMC7459884 DOI: 10.3390/life10080124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/20/2020] [Accepted: 07/22/2020] [Indexed: 01/27/2023] Open
Abstract
Parkinson’s disease (PD) is the second most common neurological disease and belongs to a group of neurodegenerative disorders called synucleinopathies in which pathological aggregates of N-terminally acetylated α-synuclein (NAcα-Syn) accumulate in various regions of the brain. In PD, these NAcα-Syn aggregates have been found to contain covalent dityrosine crosslinks, which can occur either intermolecularly or intramolecularly. Cerebral metal imbalance is also a hallmark of PD, warranting investigations into the effects of brain biometals on NAcα-Syn. NAcα-Syn is an intrinsically disordered protein, and metal-mediated conformational modifications of this structurally dynamic protein have been demonstrated to influence its propensity for dityrosine formation. In this study, a library of tyrosine-to-phenylalanine (Y-to-F) NAcα-Syn constructs were designed in order to elucidate the nature and the precise residues involved in dityrosine crosslinking of Fe-bound NAcα-Syn. The structural capacity of each mutant to form dityrosine crosslinks was assessed using Photo-Induced Cross-Linking of Unmodified Proteins (PICUP), demonstrating that coordination of either FeIII or FeII to NAcα-Syn inhibits dityrosine crosslinking among the C-terminal residues. We further demonstrate that Y39 is the main contributor to dityrosine formation of Fe-bound NAcα-Syn, while Y125 is the main residue involved in dityrosine crosslinks in unmetalated NAcα-Syn. Our results confirm that iron coordination has a global effect on NAcα-Syn structure and reactivity.
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Murgas CJ, Green SP, Forney AK, Korba RM, An SS, Kitten T, Lucas HR. Intracellular Metal Speciation in Streptococcus sanguinis Establishes SsaACB as Critical for Redox Maintenance. ACS Infect Dis 2020; 6:1906-1921. [PMID: 32329608 DOI: 10.1021/acsinfecdis.0c00132] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Streptococcus sanguinis is an oral commensal bacterium, but it can colonize pre-existing heart valve vegetations if introduced into the bloodstream, leading to infective endocarditis. Loss of Mn- or Fe-cofactored virulence determinants are thought to result in weakening of this bacterium. Indeed, intracellular Mn accumulation mediated by the lipoprotein SsaB, a component of the SsaACB transporter complex, has been shown to promote virulence for endocarditis and O2 tolerance. To delineate intracellular metal-ion abundance and redox speciation within S. sanguinis, we developed a protocol exploiting two spectroscopic techniques, Inductively coupled plasma-optical emission spectrometry (ICP-OES) and electron paramagnetic resonance (EPR) spectroscopy, to respectively quantify total intracellular metal concentrations and directly measure redox speciation of Fe and Mn within intact whole-cell samples. Addition of the cell-permeable siderophore deferoxamine shifts the oxidation states of accessible Fe and Mn from reduced-to-oxidized, as verified by magnetic moment calculations, aiding in the characterization of intracellular metal pools and metal sequestration levels for Mn2+ and Fe. We have applied this methodology to S. sanguinis and an SsaACB knockout strain (ΔssaACB), indicating that SsaACB mediates both Mn and Fe uptake, directly influencing the metal-ion pools available for biological inorganic pathways. Mn supplementation of ΔssaACB returns total intracellular Mn to wild-type levels, but it does not restore wild-type redox speciation or distribution of metal cofactor availability for either Mn or Fe. Our results highlight the biochemical basis for S. sanguinis oxidative resistance, revealing a dynamic role for SsaACB in controlling redox homeostasis by managing the intracellular Fe/Mn composition and distribution.
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Affiliation(s)
- Cody J. Murgas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Shannon P. Green
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
- Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Ashley K. Forney
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Rachel M. Korba
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Seon-Sook An
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Todd Kitten
- Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia 23298, United States
- Department of Microbiology & Immunology, Virginia Commonwealth University, Richmond, Virginia 23298, United States
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Lucas HR. Isolation of Intricate α‐Synuclein Assemblies Across the Dynamic Landscape. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.00685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fernandez RD, Lucas HR. Tetrameric α-Synuclein Stability in a Mixed Metal Environment. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Lucas HR, Fernández RD. Navigating the dynamic landscape of alpha-synuclein morphology: a review of the physiologically relevant tetrameric conformation. Neural Regen Res 2020; 15:407-415. [PMID: 31571649 PMCID: PMC6921358 DOI: 10.4103/1673-5374.265792] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
N-acetylated α-synuclein (αSyn) has long been established as an intrinsically disordered protein associated with a dysfunctional role in Parkinson's disease. In recent years, a physiologically relevant, higher order conformation has been identified as a helical tetramer that is tailored by buried hydrophobic interactions and is distinctively aggregation resistant. The canonical mechanism by which the tetramer assembles remains elusive. As novel biochemical approaches, computational methods, pioneering purification platforms, and powerful imaging techniques continue to develop, puzzling information that once sparked debate as to the veracity of the tetramer has now shed light upon this new counterpart in αSyn neurobiology. Nuclear magnetic resonance and computational studies on multimeric αSyn structure have revealed that the protein folding propensity is controlled by small energy barriers that enable large scale reconfiguration. Alternatively, familial mutations ablate tetramerization and reconfigure polymorphic fibrillization. In this review, we will discuss the dynamic landscape of αSyn quaternary structure with a focus on the tetrameric conformation.
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
| | - Ricardo D Fernández
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
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Abeyawardhane DL, Curry AM, Forney AK, Roberts JW, Lucas HR. Biometals as conformational modulators of α-synuclein photochemical crosslinking. J Biol Inorg Chem 2019; 24:1261-1268. [PMID: 31728738 PMCID: PMC7334974 DOI: 10.1007/s00775-019-01738-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Accepted: 10/26/2019] [Indexed: 11/28/2022]
Abstract
Metal dyshomeostasis has long been linked to Parkinson's disease (PD), and the amyloidogenic protein α-synuclein (αS) is universally recognized as a key player in PD pathology. Structural consequences upon coordination of copper and iron to αS have gained attention due to significant dyshomeostasis of both metals in the PD brain. Protein-metal association can navigate protein folding in distinctive pathways based on the identity of the bio-metal in question. In this work, we employed photo-chemical crosslinking of unmodified proteins (PICUP) to evaluate these potential metal ion-induced structural alterations in the folding dynamics of N-terminally acetylated αS (NAcαS) following metal coordination. Through fluorescence analysis and immunoblotting analyses following photoirradiation, we discovered that coordination of iron obstructs copper-promoted crosslinking. The absence of intra-molecular crosslinking upon iron association further supports its C-terminal coordination site and suggests a potential role for iron in mitigating nearby post-translational modification of tyrosine residues. Decreased fluorescence emission upon synergistic coordination of both copper and iron highlighted that although copper acts as a conformational promotor of NAcαS crosslinking, iron inhibits analogous conformational changes within the protein. The metal coordination preferences of NAcαS suggest that both competitive binding sites as well as dual metal coordination contribute to the changes in folding dynamics, unveiling unique structural orientations for NAcαS that have a direct and measureable influence on photoinitiated dityrosine crosslinks. Moreover, our findings have physiological implications in that iron overload, as is associated with PD-insulted brain tissue, may serve as a conformational block of copper-promoted protein oxidation.
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Affiliation(s)
| | - Alyson M Curry
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ashley K Forney
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Joel W Roberts
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Heather R Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, 23284, USA.
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Abstract
The structurally dynamic amyloidogenic protein α-synuclein (αS) is universally recognized as a key player in Parkinson's disease (PD). Copper, which acts as a neuronal signaling agent, is also an effector of αS structure, aggregation, and localization in vivo. In humans, αS is known to carry an acetyl group on the starting methionine residue, capping the N-terminal free amine which was a known high-affinity CuII binding site. We now report the first detailed characterization data using electron paramagnetic resonance (EPR) spectroscopy to describe the CuII coordination modes of N-terminally acetylated αS (NAcαS). Through use of EPR hyperfine structure analyses and the Peisach-Blumberg correlation, an N3O1 binding mode was established that involves the single histidine residue at position 50 and a lower population of a second CuII-binding mode that may involve a C-terminal contribution. We additionally generated an N-terminally acetylated disease-relevant variant, NAcH50Q, that promotes a shift in the CuII binding site to the C-terminus of the protein. Moreover, fibrillar NAcH50Q-CuII exhibits enhanced parallel β-sheet character and increased hydrophobic surface area compared to NAcαS-CuII and to both protein variants that lack a coordinated cupric ion. The results presented herein demonstrate the differential impact of distinct CuII binding sites within NAcαS, revealing that C-terminal CuII binding exacerbates the structural consequences of the H50Q missense mutation. Likewise, the global structural modifications that result from N-terminal capping augment the properties of CuII coordination. Hence, consideration of the effect of CuII on NAcαS and NAcH50Q misfolding may shed light on the extrinsic or environmental factors that influence PD pathology.
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Affiliation(s)
| | - Denver R. Heitger
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Ricardo D. Fernández
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Ashley K. Forney
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Murgas C, Forney AK, Baker S, An SS, Kitten TO, Lucas HR. Intracellular Metal Speciation in Streptococcus sanguinis is Pivotal for Redox Maintenance. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Lucas HR, Abeyawardhane DL, Fernández RD, Heitger DR, Forney AK, Murgas CJ, Curry A. Metal-Promoted Alpha-Synuclein Modifications Steer the Aggregate Conformation. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Fernández RD, Lucas HR. Isolation of recombinant tetrameric N-acetylated α-synuclein. Protein Expr Purif 2018; 152:146-154. [DOI: 10.1016/j.pep.2018.07.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 07/10/2018] [Accepted: 07/19/2018] [Indexed: 12/25/2022]
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Abeyawardhane DL, Fernández RD, Heitger DR, Crozier MK, Wolver JC, Lucas HR. Copper Induced Radical Dimerization of α-Synuclein Requires Histidine. J Am Chem Soc 2018; 140:17086-17094. [DOI: 10.1021/jacs.8b08947] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
| | - Ricardo D. Fernández
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Denver R. Heitger
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Madeleine K. Crozier
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Julia C. Wolver
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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Fernández RD, Lucas HR. Mass spectrometry data confirming tetrameric α-synuclein N-terminal acetylation. Data Brief 2018; 20:1686-1691. [PMID: 30263921 PMCID: PMC6157607 DOI: 10.1016/j.dib.2018.09.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 09/07/2018] [Accepted: 09/12/2018] [Indexed: 11/23/2022] Open
Abstract
Tetrameric α-synuclein (αS) is an elusive multimer of the dynamic neuronal protein implicated in Parkinson׳s disease. Through the data reported herein, we demonstrate that this high molecular weight multimer is N-acetylated. Coexpression of tetrameric αS in Escherichia coli with the NatB acetylase derived from yeast enables access to N-terminally acetylated αS (NAcαS), the native form in humans. Following purification and characterization as previously described by us in "Isolation of Recombinant Tetrameric N-acetylated α-synuclein" (Fernández and Lucas, 2018), the purified protein was excised from a native gel for confirmation of N-terminal acetylation. Through high-resolution mass spectrometry techniques, the identification of this helical tetramer as NAcαS has been clearly demonstrated.
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Affiliation(s)
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, VA, USA
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18
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Abeyawardhane DL, Fernández RD, Murgas CJ, Heitger DR, Forney AK, Crozier MK, Lucas HR. Iron Redox Chemistry Promotes Antiparallel Oligomerization of α-Synuclein. J Am Chem Soc 2018; 140:5028-5032. [PMID: 29608844 DOI: 10.1021/jacs.8b02013] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Brain metal dyshomeostasis and altered structural dynamics of the presynaptic protein α-synuclein (αS) are both implicated in the pathology of Parkinson's disease (PD), yet a mechanistic understanding of disease progression in the context of αS structure and metal interactions remains elusive. In this Communication, we detail the influence of iron, a prevalent redox-active brain biometal, on the aggregation propensity and secondary structure of N-terminally acetylated αS (NAcαS), the physiologically relevant form in humans. We demonstrate that under aerobic conditions, Fe(II) commits NAcαS to a PD-relevant oligomeric assembly, verified by the oligomer-selective A11 antibody, that does not have any parallel β-sheet character but contains a substantial right-twisted antiparallel β-sheet component based on CD analyses and descriptive deconvolution of the secondary structure. This NAcαS-FeII oligomer does not develop into the β-sheet fibrils that have become hallmarks of PD, even after extended incubation, as verified by TEM imaging and the fibril-specific OC antibody. Thioflavin T (ThT), a fluorescent probe for β-sheet fibril formation, also lacks coordination to this antiparallel conformer. We further show that this oligomeric state is not observed when O2 is excluded, indicating a role for iron(II)-mediated O2 chemistry in locking this dynamic protein into a conformation that may have physiological or pathological implications.
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Affiliation(s)
- Dinendra L Abeyawardhane
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Ricardo D Fernández
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Cody J Murgas
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Denver R Heitger
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Ashley K Forney
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Madeleine K Crozier
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
| | - Heather R Lucas
- Department of Chemistry , Virginia Commonwealth University , Richmond , Virginia 23284 , United States
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Wang D, Gilliland SE, Yi X, Logan K, Heitger DR, Lucas HR, Wang WN. Iron Mesh-Based Metal Organic Framework Filter for Efficient Arsenic Removal. Environ Sci Technol 2018. [PMID: 29513011 DOI: 10.1021/acs.est.7b06212] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Efficient oxidation from arsenite [As(III)] to arsenate [As(V)], which is less toxic and more readily to be adsorbed by adsorbents, is important for the remediation of arsenic pollution. In this paper, we report a metal organic framework (MIL-100(Fe)) filter to efficiently remove arsenic from synthetic groundwater. With commercially available iron mesh as a substrate, MIL-100(Fe) is implanted through an in situ growth method. MIL-100(Fe) is able to capture As(III) due to its microporous structure, superior surface area, and ample active sites for As adsorption. This approach increases the localized As concentration around the filter, where Fenton-like reactions are initiated by the Fe2+/Fe3+ sites within the MIL-100(Fe) framework to oxidize As(III) to As(V). The mechanism was confirmed by colorimetric detection of H2O2, fluorescence, and electron paramagnetic resonance detection of ·OH. With the aid of oxygen bubbling and Joule heating, the removal efficiency of As(III) can be further boosted. The MIL-100(Fe)-based filter also exhibits satisfactory structural stability and recyclability. Notably, the adsorption capacity of the filter can be regenerated satisfactorily. Our results demonstrate the potential of this filter for the efficient remediation of As contamination in groundwater.
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Lucas HR. Exploring the Role of O2 on the Metal Ion Specific Modulation of Alpha-Synuclein Structure. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Kieber-Emmons MT, Ginsbach JW, Wick PK, Lucas HR, Helton ME, Lucchese B, Suzuki M, Zuberbühler A, Karlin KD, Solomon EI. Observation of a Cu(II)(2) (μ-1,2-peroxo)/Cu(III)(2) (μ-oxo)(2) equilibrium and its implications for copper-dioxygen reactivity. Angew Chem Int Ed Engl 2014; 53:4935-9. [PMID: 24700427 PMCID: PMC4041702 DOI: 10.1002/anie.201402166] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Indexed: 11/10/2022]
Abstract
Synthesis of small-molecule Cu2 O2 adducts has provided insight into the related biological systems and their reactivity patterns including the interconversion of the Cu(II) 2 (μ-η(2) :η(2) -peroxo) and Cu(III) 2 (μ-oxo)2 isomers. In this study, absorption spectroscopy, kinetics, and resonance Raman data show that the oxygenated product of [(BQPA)Cu(I) ](+) initially yields an "end-on peroxo" species, that subsequently converts to the thermodynamically more stable "bis-μ-oxo" isomer (Keq =3.2 at -90 °C). Calibration of density functional theory calculations to these experimental data suggest that the electrophilic reactivity previously ascribed to end-on peroxo species is in fact a result of an accessible bis-μ-oxo isomer, an electrophilic Cu2 O2 isomer in contrast to the nucleophilic reactivity of binuclear Cu(II) end-on peroxo species. This study is the first report of the interconversion of an end-on peroxo to bis-μ-oxo species in transition metal-dioxygen chemistry.
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Affiliation(s)
| | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA 94305 USA, Fax: (+1) 650-725-0259
| | - Patrick K. Wick
- Department of Chemistry, University of Basel, 4056, Basel, Switzerland
| | - Heather R. Lucas
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 USA, Fax: (+1) 410-516-7044
| | - Matthew E. Helton
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 USA, Fax: (+1) 410-516-7044
| | - Baldo Lucchese
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 USA, Fax: (+1) 410-516-7044
| | - Masatatsu Suzuki
- Division of Material Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
| | | | - Kenneth D. Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218 USA, Fax: (+1) 410-516-7044
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, CA 94305 USA, Fax: (+1) 650-725-0259
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22
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Kieber-Emmons MT, Ginsbach JW, Wick PK, Lucas HR, Helton ME, Lucchese B, Suzuki M, Zuberbühler AD, Karlin KD, Solomon EI. Observation of a CuII2(μ-1,2-peroxo)/CuIII2(μ-oxo)2Equilibrium and its Implications for Copper-Dioxygen Reactivity. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201402166] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Woertink JS, Tian L, Maiti D, Lucas HR, Himes RA, Karlin KD, Neese F, Würtele C, Holthausen MC, Bill E, Sundermeyer J, Schindler S, Solomon EI. Spectroscopic and computational studies of an end-on bound superoxo-Cu(II) complex: geometric and electronic factors that determine the ground state. Inorg Chem 2011; 49:9450-9. [PMID: 20857998 DOI: 10.1021/ic101138u] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A variety of techniques including absorption, magnetic circular dichroism (MCD), variable-temperature, variable-field MCD (VTVH-MCD), and resonance Raman (rR) spectroscopies are combined with density functional theory (DFT) calculations to elucidate the electronic structure of the end-on (η(1)) bound superoxo-Cu(II) complex [TMG(3)trenCuO(2)](+) (where TMG(3)tren is 1,1,1-tris[2-[N(2)-(1,1,3,3-tetramethylguanidino)]ethyl]amine). The spectral features of [TMG(3)trenCuO(2)](+) are assigned, including the first definitive assignment of a superoxo intraligand transition in a metal-superoxo complex, and a detailed description of end-on superoxo-Cu(II) bonding is developed. The lack of overlap between the two magnetic orbitals of [TMG(3)trenCuO(2)](+) eliminates antiferromagnetic coupling between the copper(II) and the superoxide, while the significant superoxo π*(σ) character of the copper dz(2) orbital leads to its ferromagnetically coupled, triplet, ground state.
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Affiliation(s)
- Julia S Woertink
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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24
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Abstract
Interactions of copper and membranes with α-synuclein have been implicated in pathogenic mechanisms of Parkinson's disease, yet work examining both concurrently is scarce. We have examined the effect of copper(ii) on protein/vesicle binding and found that both the copper(ii) affinity and α-helical content are enhanced for the membrane-bound protein.
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Affiliation(s)
- Heather R Lucas
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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25
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Lee Y, Lee DH, Park GY, Lucas HR, Narducci Sarjeant AA, Kieber-Emmons MT, Vance MA, Milligan AE, Solomon EI, Karlin KD. Sulfur donor atom effects on copper(I)/O(2) chemistry with thioanisole containing tetradentate N(3)S ligand leading to μ-1,2-peroxo-dicopper(II) species. Inorg Chem 2011; 49:8873-85. [PMID: 20822156 DOI: 10.1021/ic101041m] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To better understand the effect of thioether coordination in copper-O(2) chemistry, the tetradentate N(3)S ligand L(ASM) (2-(methylthio)-N,N-bis((pyridin-2-yl)methyl)benzenamine) and related alkylether ligand L(EOE) (2-ethoxy-N,N-bis((pyridin-2-yl)methyl)ethanamine) have been studied. The corresponding copper(I) complexes, [(L(ASM))Cu(I)](+) (1a) and [(L(EOE))Cu(I)](+) (3a), were studied as were the related compound [(L(ESE))Cu(I)](+) (2a, L(ESE) = (2-ethylthio-N,N-bis((pyridin-2-yl)methyl)ethanamine). The X-ray structure of 1a and its solution conductivity reveal a monomeric molecular structure possessing thioether coordination which persists in solution. In contrast, the C-O stretching frequencies of the derivative Cu(I)-CO complexes reveal that for these complexes, the modulated ligand arms, whether arylthioether, alkylthioether, or ether, are not coordinated to the cuprous ion. Electrochemical data for 1a and 2a in CH(3)CN and N,N-dimethylformamide (DMF) show the thioanisole moiety to be a poor electron donor compared to alkylthioether (1a is ∼200 mV more positive than 2a). The structures of [(L(ASM))Cu(II)(CH(3)OH)](2+) (1c) and [(L(ESE))Cu(II)(CH(3)OH)](2+) (2c) have also been obtained and indicate nearly identical copper coordination environments. Oxygenation of 1a at reduced temperature gives a characteristic deep blue intermediate [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) with absorption features at 442 (1,500 M(-1) cm(-1)), 530 (8,600 M(-1) cm(-1)), and 605 nm (10,400 M(-1) cm(-1)); these values compare well to the ligand-to-metal charge-transfer (LMCT) transitions previously reported for [{(L(ESE))Cu(II)}(2)(O(2)(2-))](2+) (2b(P)). Resonance Raman data for [{(L(ASM))Cu(II)}(2)(O(2)(2-))](2+) (1b(P)) support the formation of μ-1,2-peroxo species ν(O-O) = 828 cm(-1)(Δ((18)O(2)) = 48), ν(sym)(Cu-O) = 547 cm(-1) (Δ((18)O(2)) = 23), and ν(asym)(Cu-O) = 497 cm(-1) (Δ((18)O(2)) = 22) and suggest the L(ASM) ligand is a poorer electron donor to copper than is L(ESE). In contrast, the oxygenation of [(L(EOE))Cu(I)](+) (3a), possessing an ether donor as an analogue of the thioether in L(ESE), led to the formation of a bis(μ-oxo) species [{(L(EOE))Cu(III)}(2)(O(2-))(2)](2+) (3b(O); 380 nm, ε ∼ 10,000 M(-1) cm(-1)). This result provides further support for the sulfur influence in 1b(P) and 2b(P), in particular coordination of the sulfur to the Cu. Thermal decomposition of 1b(P) is accompanied by ligand sulfoxidation. The structure of [{(L(EOE))Cu(II)(Cl)}(2)](+) (3c) generated from the reductive dehalogenation of organic chlorides suggests that the ether moiety is weakly bound to the cupric ion. A detailed discussion of the spectroscopic and structural characteristics of 1b(P), 2b(P), and 3b(O) is presented.
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Affiliation(s)
- Yunho Lee
- Department of Chemistry, the Johns Hopkins University, Baltimore, Maryland 21218, USA
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26
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Lucas HR, Meyer GJ, Karlin KD. CO and O2 binding to pseudo-tetradentate ligand-copper(I) complexes with a variable N-donor moiety: kinetic/thermodynamic investigation reveals ligand-induced changes in reaction mechanism. J Am Chem Soc 2011; 132:12927-40. [PMID: 20726586 DOI: 10.1021/ja104107q] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The kinetics, thermodynamics, and coordination dynamics are reported for O(2) and CO 1:1 binding to a series of pseudo-tetradentate ligand-copper(I) complexes ((D)LCu(I)) to give Cu(I)/O(2) and Cu(I)/CO product species. Members of the (D)LCu(I) series possess an identical tridentate core structure where the cuprous ion binds to the bispicolylamine (L) fragment. (D)L also contains a fourth variable N-donor moiety {D = benzyl (Bz); pyridyl (Py); imidazolyl (Im); dimethylamino (NMe(2)); (tert-butylphenyl)pyridyl (TBP); quinolyl (Q)}. The structural characteristics of (D)LCu(I)-CO and (D)LCu(I) are detailed, with X-ray crystal structures reported for (TBP)LCu(I)-CO, (Bz)LCu(I)-CO, and (Q)LCu(I). Infrared studies (solution and solid-state) confirm that (D)LCu(I)-CO possess the same four-coordinate core structure in solution with the variable D moiety "dangling", i.e., not coordinated to the copper(I) ion. Other trends observed for the present series appear to derive from the degree to which the D-group interacts with the cuprous ion center. Electrochemical studies reveal close similarities of behavior for (Im)LCu(I) and (NMe(2))LCu(I) (as well as for (TBP)LCu(I) and (Q)LCu(I)), which relate to the O(2) binding kinetics and thermodynamics. Equilibrium CO binding data (K(CO), ΔH°, ΔS°) were obtained by conducting UV-visible spectrophotometric CO titrations, while CO binding kinetics and thermodynamics (k(CO), ΔH(double dagger), ΔS(double dagger)) were measured through variable-temperature (193-293 K) transient absorbance laser flash photolysis experiments, λ(ex) = 355 nm. Carbon monoxide dissociation rate constants (k(-CO)) and corresponding activation parameters (ΔH(double dagger), ΔS(double dagger)) have also been obtained. CO binding to (D)LCu(I) follows an associative mechanism, with the increased donation from D leading to higher k(CO) values. Unlike observations from previous work, the K(CO) values increased as the k(CO) and k(-CO) values declined; the latter decreased at a faster rate. By using the "flash-and-trap" method (λ(ex) = 355 nm, 188-218 K), the kinetics and thermodynamics (k(O(2)), ΔH(double dagger), ΔS(double dagger)) for O(2) binding to (NMe(2))LCu(I) and (Im)LCu(I) were measured and compared to those for (Py)LCu(I). A surprising change in the O(2) binding mechanism was deduced from the thermodynamic ΔS(double dagger) values observed, associative for (Py)LCu(I) but dissociative for (NMe(2))LCu(I) and (Im)LCu(I); these results are interpreted as arising from a difference in the timing of electron transfer from copper(I) to O(2) as this molecule coordinates and a tetrahydrofuran (THF) solvent molecule dissociates. The change in mechanism was not simply related to alterations in (D)LCu(II/I) geometries or the order in which O(2) and THF coordinate. The equilibrium O(2) binding constant (K(O(2)), ΔH°, ΔS°) and O(2) dissociation rate constants (k(-O(2)), ΔH(double dagger), ΔS(double dagger)) were also determined. Overall the results demonstrate that subtle changes in the coordination environment, as occur over time through evolution in nature or through controlled ligand design in synthetic systems, dictate to a critically detailed level the observed chemistry in terms of reaction kinetics, structure, and reactivity, and thus function. Results reported here are also compared to relevant copper and/or iron biological systems and analogous synthetic ligand-copper systems.
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Fukuzumi S, Kotani H, Lucas HR, Doi K, Suenobu T, Peterson RL, Karlin KD. Mononuclear copper complex-catalyzed four-electron reduction of oxygen. J Am Chem Soc 2010; 132:6874-5. [PMID: 20443560 DOI: 10.1021/ja100538x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A mononuclear Cu(II) complex acts as an efficient catalyst for four-electron reduction of O(2) to H(2)O. Its reduction by a ferrocene derivative (Fc*) and reaction with O(2) leads to the formation of a peroxodicopper(II) complex; this is subsequently reduced by Fc* in the presence of protons to regenerate the Cu(II) complex.
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan.
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28
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Abstract
Alpha-synuclein (alpha-syn), a presynaptic protein implicated in Parkinson's disease, binds copper(II) ion (1:1) with submicromolar affinity in vitro. Insights on the molecular details of soluble- and fibrillar-Cu-alpha-syn are gained through X-ray absorption spectroscopy. Our results indicate that the copper coordination environment (3-to-4 N/O ligands, average Cu-ligand distance approximately 1.96 A) exhibits little structural rearrangement upon amyloid formation in spite of the overall polypeptide conformational change from disordered-to-beta-sheet. Interestingly, we find that some population of Cu(II)-alpha-syn reduces to Cu(I)-alpha-syn in the absence of O(2). This autoreduction event appears diminished in the presence of O(2) suggestive of preceding Cu(I)/O(2) chemistry. Evidence for generation of reactive oxygen species is obtained by the observation of new emission features attributed to dityrosine cross-links in fibrillar samples.
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Affiliation(s)
- Heather R Lucas
- Laboratory of Molecular Biophysics and Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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29
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Lee Y, Park GY, Lucas HR, Vajda PL, Kamaraj K, Vance MA, Milligan AE, Woertink JS, Siegler MA, Narducci Sarjeant AA, Zakharov LN, Rheingold AL, Solomon EI, Karlin KD. Copper(I)/O2 chemistry with imidazole containing tripodal tetradentate ligands leading to mu-1,2-peroxo-dicopper(II) species. Inorg Chem 2010; 48:11297-309. [PMID: 19886646 DOI: 10.1021/ic9017695] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cuprous and cupric complexes with the new imidazolyl containing tripodal tetradentate ligands {L(MIm), (1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine, and L(EIm), 2-(1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)ethanamine}, have been investigated to probe differences in their chemistry, especially in copper(I)-dioxygen chemistry, compared to that already known for the pyridyl analogue TMPA, tris(2-pyridyl)methyl)amine. Infrared (IR) stretching frequencies obtained from carbon monoxide adducts of [(L(MIm))Cu(I)](+) (1a) and [(L(EIm))Cu(I)](+) (2a) show that the imidazolyl donor is stronger than its pyridyl analogue. Electrochemical data suggest differences in the binding constant of Cu(II) to L(EIm) compared to TMPA and L(MIm), reflecting geometric changes. Oxygenation of [(L(MIm))Cu(I)](+) (1a) in 2-methyltetrahydrofuran (MeTHF) solvent at -128 degrees C leads to an intensely purple colored species with a UV-vis spectrum characteristic of an end-on bound peroxodicopper(II) complex [{(L(MIm))Cu(II)}(2)(mu-1,2-O(2)(2-))](2+) (1b(P)) {lambda(max) = 528 nm}, very similar to the previously well characterized complex [{(TMPA)Cu(II)}(2)(mu-1,2-O(2)(2-))](2+) {lambda(max) = 520 nm (epsilon = 12 000 M(-1) cm(-1)), in MeTHF; resonance Raman (rR) spectroscopy: nu(O-O) = 832 (Delta((18)O(2)) = -44) cm(-1)}. In the low-temperature oxygenation of 2a, benchtop (-128 degrees C) and stopped-flow (-90 degrees C) experiments reveal the formation of an initial superoxo-Cu(II) species [(L(EIm))Cu(II)(O(2)(*-))](+) (2b(S)), lambda(max) = 431 nm in THF) . This converts to the low-temperature stable peroxo complex [{(L(EIm))Cu(II)}(2)(mu-1,2-O(2)(2-))](2+) (2b(P)) {rR spectroscopy: nu(O-O) = 822 (Delta((18)O(2)) = -46) cm(-1)}. Complex 2b(P) possess distinctly reduced Cu-O and O-O stretching frequencies and a red-shifted UV-vis feature {to lambda(max) = 535 nm (epsilon = 11 000 M(-1) cm(-1))} compared to the TMPA analogue due to a distortion from trigonal bipyramidal (TBP) to a square pyramidal ligand field. This distortion is supported by the structural characterization of related ligand-copper(II) complexes: A stable tetramer cluster complex [(mu(2)-L(EIm-))(4)(Cu(II))(4)](4+), obtained from thermal decomposition of 2b(P) (with formation of H(2)O(2)), also exhibits a distorted square pyramidal Cu(II) ion geometry as does the copper(II) complex [(L(EIm))Cu(II)(CH(3)CN)](2+) (2c), characterized by X-ray crystallography and solution electron paramagnetic resonance (EPR) spectroscopy.
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Affiliation(s)
- Yunho Lee
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Lucas HR, Lee JC. Effect of dioxygen on copper(II) binding to alpha-synuclein. J Inorg Biochem 2009; 104:245-9. [PMID: 20064662 DOI: 10.1016/j.jinorgbio.2009.12.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 11/18/2009] [Accepted: 12/14/2009] [Indexed: 11/24/2022]
Abstract
Using the fluorescent amino acid tryptophan (Trp), we have characterized the copper(II) binding of F4W alpha-synuclein in the presence and absence of dioxygen at neutral pH. Variations in Trp fluorescence indicate that copper(II) binding is enhanced by the presence of dioxygen, with the apparent dissociation constant (K(d(app))) changing from 100nM (anaerobic) to 10nM (aerobic). To investigate the possible role of methionine oxidation, complementary work focused on synthetic peptide models of the N-terminal Cu(II)-alpha-syn site, MDV(F/W) and M( *)DV(F/W), where M( *)=methionine sulfoxide. Furthermore, we employed circular dichroism (CD) spectroscopy to demonstrate that the phenyl-to-indole (F-->W) substitution does not alter copper(II) binding properties and to confirm the 1:1 metal-peptide binding stoichiometry. CD comparisons also revealed that Met1 oxidation does not affect the copper-peptide conformation and further suggested the possible existence of a Cu(II)-Trp/Phe (cation-pi) interaction.
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Affiliation(s)
- Heather R Lucas
- Laboratory of Molecular Biophysics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-8013, United States
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Lucas HR, Meyer GJ, Karlin KD. Carbon monoxide and nitrogen monoxide ligand dynamics in synthetic heme and heme-copper complex systems. J Am Chem Soc 2009; 131:13924-5. [PMID: 19736941 DOI: 10.1021/ja906172c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intermolecular nitrogen monoxide (*NO) and carbon monoxide (CO) transfer from iron to copper and back, a phenomenon not previously observed, has been accomplished by employing transient-absorbance laser flash photolysis methods. A 1:1 heme/copper component system consisting of a six-coordinate ferrous species, F(8)Fe(II)(CO)(DCIM) or F(8)Fe(II)(NO)(thf) [F(8) = tetrakis(2,6-difluorophenyl)porphyrinate(2-); DCIM = 1,5-dicyclohexylimidazole; thf = tetrahydrofuran], and two ligand-copper(I) complexes, one with tridentate [(Bz)L = (benzyl)bis(2-pyridylmethyl)amine] and one with tetradentate coordination [(Py)L = tris(2-pyridylmethyl)amine], was utilized. The results suggest a lower affinity for NO versus CO binding to copper(I) and a higher rate for NO versus CO binding to heme. In fact, the latter event has been observed in cytochrome c oxidase aa(3).
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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32
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Lucas HR, Karlin KD. Copper-Carbon Bonds in Mechanistic and Structural Probing of Proteins as well as in Situations where Copper is a Catalytic or Receptor Site. Metal-Carbon Bonds in Enzymes and Cofactors 2009. [DOI: 10.1039/9781847559333-00295] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
While copper-carbon bonds are well appreciated in organometallic synthetic chemistry, such occurrences are less known in biological settings. By far, the greatest incidence of copper-carbon moieties is in bioinorganic research aimed at probing copper protein active site structure and mechanism; for example, carbon monoxide (CO) binding as a surrogate for O2. Using infrared (IR) spectroscopy, CO coordination to cuprous sites has proven to be an extremely useful tool for determining active site copper ligation (e.g., donor atom number and type). The coupled (hemocyanin, tyrosinase, catechol oxidase) and non-coupled (peptidylglycine α-hydroxylating monooxygenase, dopamine β-monooxygenase) binuclear copper proteins as well as the heme-copper oxidases (HCOs) have been studied extensively via this method. In addition, environmental changes within the vicinity of the active site have been determined based on shifts in the CO stretching frequencies, such as for copper amine oxidases, nitrite reductases and again in the binuclear proteins and HCOs. In many situations, spectroscopic monitoring has provided kinetic and thermodynamic data on CuI-CO formation and CO dissociation from copper(I); recently, processes occurring on a femtosecond timescale have been reported. Copper-cyano moieties have also been useful for obtaining insights into the active site structure and mechanisms of copper-zinc superoxide dismutase, azurin, nitrous oxide reductase, and multi-copper oxidases. Cyanide is a good ligand for both copper(I) and copper(II), therefore multiple physical-spectroscopic techniques can be applied. A more obvious occurrence of a “Cu-C” moiety was recently described for a CO dehydrogenase which contains a novel molybdenum-copper catalytic site. A bacterial copper chaperone (CusF) was recently established to have a novel d-π interaction comprised of copper(I) with the arene containing side-chain of a tryptophan amino acid residue. Meanwhile, good evidence exists that a plant receptor site (ETR1) utilizes copper(I) to sense ethylene, a growth hormone. A copper olfactory receptor has also been suggested. All of the above mentioned occurrences or uses of carbon-containing substrates and/or probes are reviewed and discussed within the framework of copper proteins and other relevant systems.
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Affiliation(s)
- Heather R. Lucas
- Department of Chemistry, The Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
| | - Kenneth D. Karlin
- Department of Chemistry, The Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
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Lucas HR, Karlin KD. Copper-Carbon Bonds in Mechanistic and Structural Probing of Proteins as well as in Situations where Copper is a Catalytic or Receptor Site. Met Ions Life Sci 2009; 6:295-361. [PMID: 20877799 DOI: 10.1039/bk9781847559159-00295] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
While copper-carbon bonds are well appreciated in organometallic synthetic chemistry, such occurrences are less known in biological settings. By far, the greatest incidence of copper-carbon moieties is in bioinorganic research aimed at probing copper protein active site structure and mechanism; for example, carbon monoxide (CO) binding as a surrogate for O(2). Using infrared (IR) spectroscopy, CO coordination to cuprous sites has proven to be an extremely useful tool for determining active site copper ligation (e.g., donor atom number and type). The coupled (hemocyanin, tyrosinase, catechol oxidase) and non-coupled (peptidylglycine α-hydroxylating monooxygenase, dopamine β-monooxygenase) binuclear copper proteins as well as the heme-copper oxidases (HCOs) have been studied extensively via this method. In addition, environmental changes within the vicinity of the active site have been determined based on shifts in the CO stretching frequencies, such as for copper amine oxidases, nitrite reductases and again in the binuclear proteins and HCOs. In many situations, spectroscopic monitoring has provided kinetic and thermodynamic data on Cu(I)-CO formation and CO dissociation from copper(I); recently, processes occurring on a femtosecond timescale have been reported. Copper-cyano moieties have also been useful for obtaining insights into the active site structure and mechanisms of copper-zinc superoxide dismutase, azurin, nitrous oxide reductase, and multi-copper oxidases. Cyanide is a good ligand for both copper(I) and copper(II), therefore multiple physical-spectroscopic techniques can be applied. A more obvious occurrence of a "Cu-C" moiety was recently described for a CO dehydrogenase which contains a novel molybdenum-copper catalytic site. A bacterial copper chaperone (CusF) was recently established to have a novel d-π interaction comprised of copper(I) with the arene containing side-chain of a tryptophan amino acid residue. Meanwhile, good evidence exists that a plant receptor site (ETR1) utilizes copper(I) to sense ethylene, a growth hormone. A copper olfactory receptor has also been suggested. All of the above mentioned occurrences or uses of carbon-containing substrates and/or probes are reviewed and discussed within the framework of copper proteins and other relevant systems.
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
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Fry HC, Lucas HR, Narducci Sarjeant AA, Karlin KD, Meyer GJ. Carbon Monoxide Coordination and Reversible Photodissociation in Copper(I) Pyridylalkylamine Compounds. Inorg Chem 2007; 47:241-56. [DOI: 10.1021/ic701903h] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- H. Christopher Fry
- The Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Heather R. Lucas
- The Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Amy A. Narducci Sarjeant
- The Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Kenneth D. Karlin
- The Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Gerald J. Meyer
- The Johns Hopkins University, Department of Chemistry, 3400 North Charles Street, Baltimore, Maryland 21218
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Affiliation(s)
- Debabrata Maiti
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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