1
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Freindorf M, Delgado AAA, Kraka E. CO bonding in hexa‐ and pentacoordinate carboxy‐neuroglobin: A quantum mechanics/molecular mechanics and local vibrational mode study. J Comput Chem 2022. [DOI: 10.1002/jcc.26973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marek Freindorf
- Department of Chemistry Southern Methodist University Dallas Texas USA
| | | | - Elfi Kraka
- Department of Chemistry Southern Methodist University Dallas Texas USA
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2
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Gallego CM, Mazzeo A, Vargas P, Suárez S, Pellegrino J, Doctorovich F. Azanone (HNO): generation, stabilization and detection. Chem Sci 2021; 12:10410-10425. [PMID: 34447533 PMCID: PMC8356739 DOI: 10.1039/d1sc02236a] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/05/2021] [Indexed: 12/14/2022] Open
Abstract
HNO (nitroxyl, azanone), joined the 'biologically relevant reactive nitrogen species' family in the 2000s. Azanone is impossible to store due to its high reactivity and inherent low stability. Consequently, its chemistry and effects are studied using donor compounds, which release this molecule in solution and in the gas phase upon stimulation. Researchers have also tried to stabilize this elusive species and its conjugate base by coordination to metal centers using several ligands, like metalloporphyrins and pincer ligands. Given HNO's high reactivity and short lifetime, several different strategies have been proposed for its detection in chemical and biological systems, such as colorimetric methods, EPR, HPLC, mass spectrometry, fluorescent probes, and electrochemical analysis. These approaches are described and critically compared. Finally, in the last ten years, several advances regarding the possibility of endogenous HNO generation were made; some of them are also revised in the present work.
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Affiliation(s)
- Cecilia Mariel Gallego
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Agostina Mazzeo
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Paola Vargas
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Sebastián Suárez
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Juan Pellegrino
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
| | - Fabio Doctorovich
- Departamento de Química Inorgánica, Analítica, y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, INQUIMAE-CONICET, Ciudad Universitaria Pab. 2 C1428EHA Buenos Aires Argentina
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3
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Shi Y, Michael MA, Zhang Y. HNO to NO Conversion Mechanism with Copper Zinc Superoxide Dismutase, Comparison with Heme Protein Mediated Conversions, and the Origin of Questionable Reversibility. Chemistry 2021; 27:5019-5027. [PMID: 33398888 DOI: 10.1002/chem.202100015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Indexed: 11/08/2022]
Abstract
The interconversion of NO and HNO, via copper zinc superoxide dismutase (CuZnSOD), is important in biomedicine and for HNO detection. Many mechanistic questions, including the decades-long debate on reversibility, were resolved in this work. Calculations of various active-site and full-protein models show that the basic mechanism is proton-coupled electron transfer with a computed barrier of 10.98 kcal mol-1 , which is in excellent agreement with experimental results (10.62 kcal mol-1 ), and this nonheme protein-mediated reaction has many significant mechanistic differences compared with the conversions mediated by heme proteins due to geometric and electronic factors. The reasons for the irreversible nature of this conversion and models with the first thermodynamically favorable and kinetically feasible mechanism for the experimental reverse reaction were discovered. Such results are the first for nonheme enzyme mediated HNO to NO conversions, which shall facilitate other related studies and HNO probe development.
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Affiliation(s)
- Yelu Shi
- Department of Chemistry and Chemical Biology, Stevens Institute, of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA.,College of Science and Technology, Wenzhou-Kean University, 88 Daxue Rd, Wenzhou, Zhejiang, 325060, P.R. China
| | - Matthew A Michael
- Department of Chemistry and Chemical Biology, Stevens Institute, of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute, of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA
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4
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Zou W, Tao Y, Freindorf M, Cremer D, Kraka E. Local vibrational force constants – From the assessment of empirical force constants to the description of bonding in large systems. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137337] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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5
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Rahman MH, Liu Y, Ryan MD. Proton Transfer versus Hydrogen Bonding in a Reduced Iron Porphyrin Nitrosyl Complex. Inorg Chem 2019; 58:13788-13795. [PMID: 31565930 DOI: 10.1021/acs.inorgchem.9b01447] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 1H NMR spectra of Fe(OEP)(HNO), which was formed from Fe(OEP)(NO)- in the presence of 3,5-dichlorophenol, were studied as a function of temperature. The chemical shift of the HNO proton showed a unique behavior which could be explained based on the equilibrium between the protonated complex, Fe(OEP)(HNO), and the hydrogen-bonded complex, Fe(OEP)(NO)-···HOPh. This equilibrium was consistent with UV/visible spectroscopy and the voltammetric data. UV/visible stopped-flow experiments showed that the hydrogen-bonded complex, which was formed when weak acids such as phenol were added, and the Fe(OEP)(HNO) complex were quite similar. In addition to the HNO proton resonance, the meso-resonances were consistent with the proposed equilibrium. Density functional theory calculations of various Fe(OEP)(NO)-/Fe(OEP)(HNO) species were calculated, and the results were consistent with experimental data.
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Affiliation(s)
- Md Hafizur Rahman
- Chemistry Department , Marquette University , PO Box 1881, Milwaukee , Wisconsin 53201 , United States
| | - Yilin Liu
- Chemistry Department , Marquette University , PO Box 1881, Milwaukee , Wisconsin 53201 , United States
| | - Michael D Ryan
- Chemistry Department , Marquette University , PO Box 1881, Milwaukee , Wisconsin 53201 , United States
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6
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Zhou Y, Xing YF, Wen J, Ma HB, Wang FB, Xia XH. Axial ligands tailoring the ORR activity of cobalt porphyrin. Sci Bull (Beijing) 2019; 64:1158-1166. [PMID: 36659687 DOI: 10.1016/j.scib.2019.07.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/18/2019] [Accepted: 06/26/2019] [Indexed: 01/21/2023]
Abstract
In an effort to provide visualization and understanding to the electronic "push effect" of axial ligands on the catalytic activity of cobalt macrocyclic molecules, we design a simple model system involving an [5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin]cobalt(II) (TMMPCo) monolayer axially-coordinated on thiol ligand modified Au electrode and explore the activity of the axial-ligand coordinated TMPPCo toward oxygen reduction reaction (ORR) in acidic medium. Three different ligands, with a decreasing order of coordinating ability as: 4-mercaptopyridine (MPy) > 4-aminothiolphenol (APT) > 4-mercaptobenzonitrile (MBN) are used and a maximum difference in ORR onset potential of 80 mV is observed between the MPy (highest onset potential) and MBN systems (lowest onset potential). The ORR activity of TMPPCo increases with the increase in binding strength of the axial ligand. A detailed mechanism study reveals that ORR on the three ligand coordinated TMPPCo systems shares the same 2-electron mechanism with H2O2 as the terminal product. Theoretical calculation into the structure of the ligand coordinated cobalt porphyrins uncovers the variation in atomic charge of the Co(II) center and altered frontier molecular orbital distribution among the three ligand systems. Both properties have great influence on the back-bonding formation between the Co(II) center and O2 molecules, which has been suggested to be critical toward the O2 adsorption and subsequent activation process.
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Affiliation(s)
- Yue Zhou
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Yong-Fang Xing
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jing Wen
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hai-Bo Ma
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Feng-Bin Wang
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
| | - Xing-Hua Xia
- School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
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7
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Zhang Y. Computational Investigations of Heme Carbenes and Heme Carbene Transfer Reactions. Chemistry 2019; 25:13231-13247. [DOI: 10.1002/chem.201901984] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/19/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Yong Zhang
- Department of Chemistry and Chemical Biology Stevens Institute of Technology 1 Castle Point on Hudson Hoboken NJ 07030 USA
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8
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Khade RL, Chandgude AL, Fasan R, Zhang Y. Mechanistic Investigation of Biocatalytic Heme Carbenoid Si-H Insertions. ChemCatChem 2019; 11:3101-3108. [PMID: 31428208 PMCID: PMC6699785 DOI: 10.1002/cctc.201801755] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Indexed: 12/28/2022]
Abstract
Recent studies reported the development of biocatalytic heme carbenoid Si-H insertions for the selective formation of carbon-silicon bonds, but many mechanistic questions remain unaddressed. To this end, a DFT mechanistic investigation was performed which reveals an FeII-based concerted hydride transfer mechanism with early transition state feature. The results from these computational analyses are consistent with experimental data of radical trapping, kinetic isotope effects, and structure-reactivity data using engineered variants of hemoproteins. Detailed geometric and electronic profiles along the heme catalyzed Si-H insertion pathways were provided to help understand the origin of experimental reactivity trends. Quantitative relationships between reaction barriers and some properties such as charge transfer from substrate to heme carbene and Si-H bond length change from reactant to transition state were found. Results suggest catalyst modifications to facilitate the charge transfer from the silane substrate to the carbene, which was determined to be a major electronic driving force of this reaction, should enable the development of improved biocatalysts for Si-H carbene insertion reactions.
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Affiliation(s)
- Rahul L Khade
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, NJ 07030 (USA)
| | - Ajay L Chandgude
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, NY 14627 (USA)
| | - Rudi Fasan
- Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, NY 14627 (USA)
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, NJ 07030 (USA)
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Double-Blind Clinical Trial of Arginine Supplementation in the Treatment of Adult Patients with Sickle Cell Anaemia. Adv Hematol 2019; 2019:4397150. [PMID: 30853991 PMCID: PMC6378076 DOI: 10.1155/2019/4397150] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/22/2018] [Accepted: 01/15/2019] [Indexed: 12/21/2022] Open
Abstract
Background Sickle cell anaemia (SCA) is the most prevalent monogenic disease in Brazil. In SCA, haemoglobin S (HbS) is formed, which modifies red blood cell morphology. Intravascular haemolysis occurs, in which free Hb and free radicals degrade nitric oxide (NO) and release arginase, which reduces arginine levels. Because arginine is a substrate for NO formation, this decrease leads to reduced NO (vasodilator) synthesis. SCA treatment uses hydroxyurea (HU) to maintain high foetal haemoglobin (HbF) levels and reduces HbS to avoid haemolytic episodes. Objective To analyse the efficacy of L-arginine as an adjuvant in the treatment of SCA patients. Setting The State Blood Centre of Ceará, Brazil. Methods This was a randomized double-blind clinical study of adults with SCA with continuous use of HU at the State Blood Centre of Ceará. The clinical study enrolled 25 patients receiving HU + L-arginine (500 mg) and 25 patients receiving HU + placebo. The treatment was carried out over four months. Laboratory tests were performed to determine the levels of the following: (1) complete blood count; (2) nitrite + nitrate; (3) HbF; and (4) reticulocytes. The clinical experiments were performed by a haematologist. The main outcome measures were nitrite and pain. Results Statistical analysis showed that the levels of NO were increased in the study group, and there was also a reduction in pain frequency using a pain frequency scale by day, week, and month. The levels of nitrite plus nitrate in the group receiving placebo plus HU did not change among the times evaluated (38.27 ± 17.27 mg/L, 39.49 ± 12.84 mg/L, 34.45 ± 11.25 mg/L, p >0.05), but in the patients who received supplementation with L-arginine plus HU, a significant increase in nitrite plus nitrate levels was observed between M0 and M4 (36.55 ± 20.23 mg/L versus 48.64 ± 20.63 mg/L, p =0.001) and M2 and M4 (35.71 ± 15.11 mg/L versus 48.64 ± 20.63 mg/L, p <0.001). It is important to note that the increase in nitrite plus nitrate levels occurred only in the fourth month of follow-up of patients in the treatment group, showing that at least 4 months of supplementation with L-arginine is necessary to show an increase in these metabolites in the serum. Conclusion The use of L-arginine as a coadjuvant in the treatment of sickle cell anaemia may function as a potential tool for pain relief, consequently improving the life of patients.
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10
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Shi Y, Zhang Y. Mechanisms of HNO Reactions with Ferric Heme Proteins. Angew Chem Int Ed Engl 2018; 57:16654-16658. [PMID: 30347123 PMCID: PMC6522253 DOI: 10.1002/anie.201807699] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Indexed: 02/06/2023]
Abstract
Many HNO-scavenging pathways exist to regulate its biological and pharmacological activities. Such reactions often involve ferric heme proteins and form an important basis for HNO probe development. However, mechanisms of HNO reactions with ferric heme proteins are largely unknown. We performed a computational investigation using metmyoglobin and catalase as representative ferric heme proteins with neutral and negatively charged axial ligands to provide the first detailed pathways. The results reproduced experimental barriers well with an average error of 0.11 kcal mol-1 . The rate-limiting step was found to be dissociation of the resting ligand or HNO coordination when there is no resting ligand. For both heme proteins, in contrast to the non-heme case, the reductive nitrosylation step was found to be barrierless proton-coupled electron transfer, which provides the major thermodynamic driving force for the overall reaction. The origin of the difference in reactivity between metmyoglobin and catalase was also revealed.
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Affiliation(s)
- Yelu Shi
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, 1 Castle Point on Hudson, Hoboken, NJ, 07030, USA
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11
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12
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Zhang L, Zhou J, Ma F, Wang Q, Xu H, Ju H, Lei J. Single‐Sided Competitive Axial Coordination of G‐Quadruplex/Hemin as Molecular Switch for Imaging Intracellular Nitric Oxide. Chemistry 2018; 25:490-494. [DOI: 10.1002/chem.201804897] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/03/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Lei Zhang
- State Key Laboratory of Analytical Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210023 P.R. China
- School of Chemistry and Molecular Engineering, Institute of, Advanced SynthesisJiangsu National Synergetic Innovation Center for, Advanced MaterialsNanjing Tech University Nanjing 211816 P.R. China
| | - Jun Zhou
- State Key Laboratory of Analytical Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210023 P.R. China
| | - Fengjiao Ma
- State Key Laboratory of Analytical Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210023 P.R. China
| | - Quanbo Wang
- Laboratory of Immunology for Environment and HealthShandong Analysis and Test CenterShandong Academy of Sciences Jinan 250014 P.R. China
| | - Hui Xu
- School of Chemistry and Molecular Engineering, Institute of, Advanced SynthesisJiangsu National Synergetic Innovation Center for, Advanced MaterialsNanjing Tech University Nanjing 211816 P.R. China
| | - Huangxian Ju
- State Key Laboratory of Analytical Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210023 P.R. China
| | - Jianping Lei
- State Key Laboratory of Analytical Chemistry for Life ScienceSchool of Chemistry and Chemical EngineeringNanjing University Nanjing 210023 P.R. China
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Wang B, Shi Y, Tejero J, Powell SM, Thomas LM, Gladwin MT, Shiva S, Zhang Y, Richter-Addo GB. Nitrosyl Myoglobins and Their Nitrite Precursors: Crystal Structural and Quantum Mechanics and Molecular Mechanics Theoretical Investigations of Preferred Fe -NO Ligand Orientations in Myoglobin Distal Pockets. Biochemistry 2018; 57:4788-4802. [PMID: 29999305 PMCID: PMC6474360 DOI: 10.1021/acs.biochem.8b00542] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The globular dioxygen binding heme protein myoglobin (Mb) is present in several species. Its interactions with the simple nitrogen oxides, namely, nitric oxide (NO) and nitrite, have been known for decades, but the physiological relevance has only recently become more fully appreciated. We previously reported the O-nitrito mode of binding of nitrite to ferric horse heart wild-type (wt) MbIII and human hemoglobin. We have expanded on this work and report the interactions of nitrite with wt sperm whale (sw) MbIII and its H64A, H64Q, and V68A/I107Y mutants whose dissociation constants increase in the following order: H64Q < wt < V68A/I107Y < H64A. We also report their X-ray crystal structures that reveal the O-nitrito mode of binding of nitrite to these derivatives. The MbII-mediated reductions of nitrite to NO and structural data for the wt and mutant MbII-NOs are described. We show that their FeNO orientations vary with distal pocket identity, with the FeNO moieties pointing toward the hydrophobic interiors when the His64 residue is present but toward the hydrophilic exterior when this His64 residue is absent in this set of mutants. This correlates with the nature of H-bonding to the bound NO ligand (nitrosyl O vs N atom). Quantum mechanics and hybrid quantum mechanics and molecular mechanics calculations help elucidate the origin of the experimentally preferred NO orientations. In a few cases, the calculations reproduce the experimentally observed orientations only when the whole protein is taken into consideration.
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Affiliation(s)
- Bing Wang
- Price Family Foundation Institute of Structural Biology, and Department of Chemistry and Biochemistry,
University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019
| | - Yelu Shi
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson,
Hoboken, NJ 07030
| | - Jesús Tejero
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh School of Medicine, 3550 Terrace
Street, Pittsburgh, PA 15261
| | - Samantha M. Powell
- Price Family Foundation Institute of Structural Biology, and Department of Chemistry and Biochemistry,
University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019
| | - Leonard M. Thomas
- Price Family Foundation Institute of Structural Biology, and Department of Chemistry and Biochemistry,
University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019
| | - Mark T. Gladwin
- Heart, Lung, Blood and Vascular Medicine Institute, University of Pittsburgh School of Medicine, 3550 Terrace
Street, Pittsburgh, PA 15261
| | - Sruti Shiva
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA
15213
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Castle Point on Hudson,
Hoboken, NJ 07030
| | - George B. Richter-Addo
- Price Family Foundation Institute of Structural Biology, and Department of Chemistry and Biochemistry,
University of Oklahoma, 101 Stephenson Parkway, Norman, OK 73019
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Wei Y, Tinoco A, Steck V, Fasan R, Zhang Y. Cyclopropanations via Heme Carbenes: Basic Mechanism and Effects of Carbene Substituent, Protein Axial Ligand, and Porphyrin Substitution. J Am Chem Soc 2018; 140:1649-1662. [PMID: 29268614 PMCID: PMC5875692 DOI: 10.1021/jacs.7b09171] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
Catalytic carbene
transfer to olefins is a useful approach to synthesize
cyclopropanes, which are key structural motifs in many drugs and biologically
active natural products. While catalytic methods for olefin cyclopropanation
have largely relied on rare transition-metal-based catalysts, recent
studies have demonstrated the promise and synthetic value of iron-based
heme-containing proteins for promoting these reactions with excellent
catalytic activity and selectivity. Despite this progress, the mechanism
of iron-porphyrin and hemoprotein-catalyzed olefin cyclopropanation
has remained largely unknown. Using a combination of quantum chemical
calculations and experimental mechanistic analyses, the present study
shows for the first time that the increasingly useful C=C functionalizations
mediated by heme carbenes feature an FeII-based, nonradical,
concerted nonsynchronous mechanism, with early transition state character.
This mechanism differs from the FeIV-based, radical, stepwise
mechanism of heme-dependent monooxygenases. Furthermore, the effects
of the carbene substituent, metal coordinating axial ligand, and porphyrin
substituent on the reactivity of the heme carbenes was systematically
investigated, providing a basis for explaining experimental reactivity
results and defining strategies for future catalyst development. Our
results especially suggest the potential value of electron-deficient
porphyrin ligands for increasing the electrophilicity and thus the
reactivity of the heme carbene. Metal-free reactions were also studied
to reveal temperature and carbene substituent effects on catalytic
vs noncatalytic reactions. This study sheds new light into the mechanism
of iron-porphyrin and hemoprotein-catalyzed cyclopropanation reactions
and it is expected to facilitate future efforts toward sustainable
carbene transfer catalysis using these systems.
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Affiliation(s)
- Yang Wei
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology , 1 Castle Point on Hudson, Hoboken, New Jersey 07030, United States of America
| | - Antonio Tinoco
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States of America
| | - Viktoria Steck
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States of America
| | - Rudi Fasan
- Department of Chemistry, University of Rochester , 120 Trustee Road, Rochester, New York 14627, United States of America
| | - Yong Zhang
- Department of Chemistry and Chemical Biology, Stevens Institute of Technology , 1 Castle Point on Hudson, Hoboken, New Jersey 07030, United States of America
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