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Teng Q, Wu H, Sun H, Liu Y, Wang H, Wang ZG. Switchable Enzyme-mimicking catalysts Self-Assembled from de novo designed peptides and DNA G-quadruplex/hemin complex. J Colloid Interface Sci 2022; 628:1004-1011. [PMID: 35970126 DOI: 10.1016/j.jcis.2022.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/25/2022] [Accepted: 08/01/2022] [Indexed: 01/02/2023]
Abstract
Reconstruction of enzymatic active site in an artificial system is key to achieving high catalytic efficiency. Herein, we report the self-assembly of the lysine-containing peptides with guanine-rich DNA and hemin to form peroxidase-mimicking active sites and catalytic nanoparticles. The DNA strand self-folds into a G-quadruplex structure that provides a supramolecular scaffold and a potential axial ligand for hemin. The β-sheet forming capability of the lysine-containing peptides is found to affect the catalytic synergy between the G-quadruplex DNA and the peptide. It is hypothesized that the β-sheet formation of the peptides results in the enrichment of the lysine residues, which distribute on the distal side of hemin to promote the formation of Compound I, like distal arginine residue in natural heme pocket. Incorporation of the histidine residues into the lysine-containing peptides further enhanced the hemin activities, indicating the cooperation between the lysine and histidine. Furthermore, the peptide/DNA/hemin complexes can be switched between active and inactive state by reversible formation and deformation of the DNA G-quadruplex, which was attributed to the peptides-promoted conformational changes of the DNA components. This work opens an avenue to mimic the catalytic residues and their spatial distribution in the natural enzymes, and shed light on the design of the smart biocatalysts that can respond to the environmental stimuli.
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Affiliation(s)
- Qiao Teng
- State Key Laboratory of Organic-Inorganic Composites, Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology, Ministry of Education), Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Haifeng Wu
- State Key Laboratory of Organic-Inorganic Composites, Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology, Ministry of Education), Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hao Sun
- State Key Laboratory of Organic-Inorganic Composites, Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology, Ministry of Education), Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yuanxi Liu
- State Key Laboratory of Organic-Inorganic Composites, Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology, Ministry of Education), Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hui Wang
- Laboratory of Theoretical and Computational Nanoscience, CAS Center for Excellence in Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhen-Gang Wang
- State Key Laboratory of Organic-Inorganic Composites, Key Lab of Biomedical Materials of Natural Macromolecules (Beijing University of Chemical Technology, Ministry of Education), Beijing Laboratory of Biomedical Materials, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
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2
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Guo Y, Zhao H, Lin Z, Ye T, Xu D, Zeng Q. Heme in Cardiovascular Diseases: A Ubiquitous Dangerous Molecule Worthy of Vigilance. Front Cell Dev Biol 2022; 9:781839. [PMID: 35127704 PMCID: PMC8807526 DOI: 10.3389/fcell.2021.781839] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/13/2021] [Indexed: 12/20/2022] Open
Abstract
Heme, the protoporphyrin IX iron complex is widely present in the human body and it is involved in oxygen storage, electron transfer, and enzymatic reactions. However, free heme can be toxic as it catalyzes the production of reactive oxygen species, oxidizes lipids and proteins, and causes DNA damage, thereby inducing a pro-inflammatory environment. The generation, metabolism, and degradation of heme in the human body are regulated by precise mechanisms to ensure that heme remains non-toxic. However, in several types of cardiovascular diseases, impaired metabolism and exposure to heme may occur in pathological processes, including neovascularization, internal hemorrhage, ischemia, and reperfusion. Based on years of research, in this review, we aimed to summarize the underlying mechanisms by which heme contributes to the development of cardiovascular diseases through oxidative stress, relative pathway gene expression regulation and phenotypic changes in cells. Excess heme plays a detrimental role in atherosclerosis, heart failure, myocardial ischemia-reperfusion injury, degenerative aortic valve stenosis, cardiac iron overload. Recent researches revealed that in some cases heme involved in cardiac damage though ferroptosis. Thus, heme concentrations beyond normal levels are dangerous. Further research on the role of heme in cardiovascular diseases is needed.
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Affiliation(s)
- Yuyang Guo
- State Key Laboratory of Organ Failure Research, Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Hengli Zhao
- State Key Laboratory of Organ Failure Research, Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Zhibin Lin
- State Key Laboratory of Organ Failure Research, Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
| | - Taochun Ye
- Department of Cardiopulmonary Rehabilitation, First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Dingli Xu
- State Key Laboratory of Organ Failure Research, Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
- *Correspondence: Qingchun Zeng, ; Dingli Xu,
| | - Qingchun Zeng
- State Key Laboratory of Organ Failure Research, Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Shock and Microcirculation, Southern Medical University, Guangzhou, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou, China
- *Correspondence: Qingchun Zeng, ; Dingli Xu,
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3
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Wang T, Bi X, Wang L, Liu M, Yu WW, Zhu Z, Sui N. Biomimetic design of graphdiyne supported hemin for enhanced peroxidase-like activity. J Colloid Interface Sci 2021; 607:470-478. [PMID: 34509729 DOI: 10.1016/j.jcis.2021.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/09/2021] [Accepted: 09/02/2021] [Indexed: 02/07/2023]
Abstract
Effective electronic interactions between molecular catalysts and supports are critical for heterogeneous enzyme mimics, yet they are frequently neglected in most catalyst designs. Taking the enzyme mimics of hemin immobilized on graphdiyne (Hemin-GDY) as an example, we explicate for the first time the underlying role of GDY as a co-catalyst. Based on the robust conjugation between GDY and hemin, the delocalized π-electrons in GDY act as a ligand for Fe ions so that the orbital interactions including electron transport from GDY → Fe can induce the formation of an electron-rich Fe center and an electron-deficient π-electron conjugated system. This mechanism was validated by electron paramagnetic resonance (EPR), Raman spectroscopy, and DFT calculations. Moreover, both EPR spetra and Lineweaver-Burk plots revealed that Hemin-GDY could efficiently catalyze the decomposition of hydrogen peroxide (H2O2) to produce hydroxyl radical (•OH) and superoxide anion (O2•-) by a ping-pong type catalytic mechanism, and particularly, the catalytic activity was increased by 2.3-fold comparing to that of hemin immobilized on graphene (Hemin-GR). In addition, Hemin-GDY with the exceptional activity and stability was demonstrated for efficient catalytic degradation of organic pollutants under acidic conditions. Collectively, this work provides a theoretical basis for the design of GDY supported catalysts and renders great promises of the GDY based enzyme mimics.
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Affiliation(s)
- Tao Wang
- College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China
| | - Xuelong Bi
- College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China; College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China
| | - Lina Wang
- College of Environment and Safety Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China.
| | - Manhong Liu
- College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China
| | - William W Yu
- Department of Chemistry and Physics, Louisiana State University Shreveport, Shreveport, LA 71115, USA
| | - Zhiling Zhu
- College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China.
| | - Ning Sui
- College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, China.
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4
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Wang Z, Li Y, Wang H, Wan K, Liu Q, Shi X, Ding B. Enzyme Mimic Based on a Self‐Assembled Chitosan/DNA Hybrid Exhibits Superior Activity and Tolerance. Chemistry 2019; 25:12576-12582. [DOI: 10.1002/chem.201902509] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/15/2019] [Indexed: 01/08/2023]
Affiliation(s)
- Zhen‐Gang Wang
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
- State Key Laboratory of Organic-Inorganic CompositesBeijing University of Chemical Technology Beijing 100029 China
| | - Yunzhe Li
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
| | - Hui Wang
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
| | - Kaiwei Wan
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Qing Liu
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
| | - Xinghua Shi
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Baoquan Ding
- CAS Key Laboratory of Nanosystem and Hierarchical FabricationLaboratory of Theoretical and Computational NanoscienceCAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology 11 BeiYiTiao, ZhongGuanCun Beijing 100190 China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
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5
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Wang ZG, Wang H, Liu Q, Duan F, Shi X, Ding B. Designed Self-Assembly of Peptides with G-Quadruplex/Hemin DNAzyme into Nanofibrils Possessing Enzyme-Mimicking Active Sites and Catalytic Functions. ACS Catal 2018. [DOI: 10.1021/acscatal.8b00896] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zhen-Gang Wang
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
| | - Hui Wang
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
| | - Qing Liu
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
| | - Fangyuan Duan
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
| | - Xinghua Shi
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Baoquan Ding
- CAS Key Laboratory of Nanosystem and Hierarchial Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
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6
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Ponka P, Sheftel AD, English AM, Scott Bohle D, Garcia-Santos D. Do Mammalian Cells Really Need to Export and Import Heme? Trends Biochem Sci 2017; 42:395-406. [PMID: 28254242 DOI: 10.1016/j.tibs.2017.01.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/13/2017] [Accepted: 01/26/2017] [Indexed: 01/07/2023]
Abstract
Heme is a cofactor that is essential to almost all forms of life. The production of heme is a balancing act between the generation of the requisite levels of the end-product and protection of the cell and/or organism against any toxic substrates, intermediates and, in this case, end-product. In this review, we provide an overview of our understanding of the formation and regulation of this metallocofactor and discuss new research on the cell biology of heme homeostasis, with a focus on putative transmembrane transporters now proposed to be important regulators of heme distribution. The main text is complemented by a discussion dedicated to the intricate chemistry and biochemistry of heme, which is often overlooked when new pathways of heme transport are conceived.
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Affiliation(s)
- Prem Ponka
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, QC, H3T 1E2, Canada; Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada.
| | - Alex D Sheftel
- Spartan Bioscience Inc., Ottawa, ON, K2H 1B2, Canada; High Impact Editing, Ottawa, ON, K1B 3Y6, Canada
| | - Ann M English
- Department of Chemistry and Biochemistry, Centre for Research in Molecular Modeling and PROTEO, Concordia University, Montréal, QC, H4B 1R, Canada
| | - D Scott Bohle
- Department of Chemistry, McGill University, Montréal, QC, H3A 0B8, Canada
| | - Daniel Garcia-Santos
- Lady Davis Institute for Medical Research, Jewish General Hospital, Montréal, QC, H3T 1E2, Canada; Department of Physiology, McGill University, Montréal, QC, H3G 1Y6, Canada
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7
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Smalley JW, Olczak T. Heme acquisition mechanisms of Porphyromonas gingivalis - strategies used in a polymicrobial community in a heme-limited host environment. Mol Oral Microbiol 2016; 32:1-23. [PMID: 26662717 DOI: 10.1111/omi.12149] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2015] [Indexed: 01/14/2023]
Abstract
Porphyromonas gingivalis, a main etiologic agent and key pathogen responsible for initiation and progression of chronic periodontitis requires heme as a source of iron and protoporphyrin IX for its survival and the ability to establish an infection. Porphyromonas gingivalis is able to accumulate a defensive cell-surface heme-containing pigment in the form of μ-oxo bisheme. The main sources of heme for P. gingivalis in vivo are hemoproteins present in saliva, gingival crevicular fluid, and erythrocytes. To acquire heme, P. gingivalis uses several mechanisms. Among them, the best characterized are those employing hemagglutinins, hemolysins, and gingipains (Kgp, RgpA, RgpB), TonB-dependent outer-membrane receptors (HmuR, HusB, IhtA), and hemophore-like proteins (HmuY, HusA). Proteins involved in intracellular heme transport, storage, and processing are less well characterized (e.g. PgDps). Importantly, P. gingivalis may also use the heme acquisition systems of other bacteria to fulfill its own heme requirements. Porphyromonas gingivalis displays a novel paradigm for heme acquisition from hemoglobin, whereby the Fe(II)-containing oxyhemoglobin molecule must first be oxidized to methemoglobin to facilitate heme release. This process not only involves P. gingivalis arginine- and lysine-specific gingipains, but other proteases (e.g. interpain A from Prevotella intermedia) or pyocyanin produced by Pseudomonas aeruginosa. Porphyromonas gingivalis is then able to fully proteolyze the more susceptible methemoglobin substrate to release free heme or to wrest heme from it directly through the use of the HmuY hemophore.
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Affiliation(s)
- J W Smalley
- School of Dentistry, University of Liverpool, Liverpool, UK
| | - T Olczak
- Laboratory of Biochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław, Poland
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8
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Magerusan L, Socaci C, Pogacean F, Rosu MC, Biris AR, Coros M, Turza A, Floare-Avram V, Katona G, Pruneanu S. Enhancement of peroxidase-like activity of N-doped graphene assembled with iron-tetrapyridylporphyrin. RSC Adv 2016. [DOI: 10.1039/c6ra15414j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Non-covalently iron-porphyrin functionalized N-doped graphene shows a higher peroxidase-like activity than its building blocks alone.
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Affiliation(s)
- L. Magerusan
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - C. Socaci
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - F. Pogacean
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - M.-C. Rosu
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - A. R. Biris
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - M. Coros
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - A. Turza
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - V. Floare-Avram
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
| | - G. Katona
- Faculty of Chemistry and Chemical Engineering
- Babes-Bolyai University
- Cluj-Napoca
- Romania
| | - S. Pruneanu
- National Institute for Research and Development of Isotopic and Molecular Technologies
- 400293 Cluj-Napoca
- Romania
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9
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Kuter D, Streltsov V, Davydova N, Venter GA, Naidoo KJ, Egan TJ. Molecular structures and solvation of free monomeric and dimeric ferriheme in aqueous solution: insights from molecular dynamics simulations and extended X-ray absorption fine structure spectroscopy. Inorg Chem 2014; 53:10811-24. [PMID: 25275882 DOI: 10.1021/ic500454d] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CHARMM force field parameters have been developed to model nonprotein bound five-coordinate ferriheme (ferriprotoporphyrin IX) species in aqueous solution. Structures and solvation were determined from molecular dynamics (MD) simulations at 298 K of monomeric [HO-ferriheme](2-), [H2O-ferriheme](-), and [H2O-ferriheme](0); π-π dimeric [(HO-ferriheme)2](4-), [(H2O-ferriheme)(HO-ferriheme)](3-), [(H2O-ferriheme)2](2-), and [(H2O-ferriheme)2](0); and μ-oxo dimeric [μ-(ferriheme)2O](4-). Solvation of monomeric species predominated around the axial ligand, meso-hydrogen atoms of the porphyrin ring (Hmeso), and the unligated face. Existence of π-π ferriheme dimers in aqueous solution was supported by MD calculations where such dimers remained associated over the course of the simulation. Porphyrin rings were essentially coplanar. In these dimers major and minor solvation was observed around the axial ligand and Hmeso positions, respectively. In μ-oxo ferriheme, strong solvation of the unligated face and bridging oxide ligand was observed. The solution structure of the μ-oxo dimer was investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS spectrum obtained from frozen solution was markedly different from that recorded on dried μ-oxo ferriheme solid. Inclusion of five solvent molecules obtained from spatial distribution functions in the structure generated from MD simulation was required to produce acceptable fits to the EXAFS spectra of the dimer in solution, while the solid was suitably fitted using the crystal structure of μ-oxo ferriheme dimethyl ester which included no solvent molecules.
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Affiliation(s)
- David Kuter
- Scientific Computing Research Unit, †Department of Chemistry, University of Cape Town , Private Bag, Rondebosch 7701, South Africa
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10
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Qu R, Shen L, Chai Z, Jing C, Zhang Y, An Y, Shi L. Hemin-block copolymer micelle as an artificial peroxidase and its applications in chromogenic detection and biocatalysis. ACS APPLIED MATERIALS & INTERFACES 2014; 6:19207-16. [PMID: 25286878 DOI: 10.1021/am505232h] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Following an inspiration from the fine structure of natural peroxidases, such as horseradish peroxidase (HRP), an artificial peroxidase was constructed through the self-assembly of diblock copolymers and hemin, which formed a functional micelle with peroxidase-like activity. The pyridine moiety in block copolymer poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG-b-P4VP) can coordinate with hemin, and thus hemin is present in a five-coordinate complex with an open site for binding substrates, which mimics the microenvironment of heme in natural peroxidases. The amphiphilic core-shell structure of the micelle and the coordination interaction of the polymer to the hemin inhibit the formation of hemin μ-oxo dimers, and thereby enhance the stability of hemin in the water phase. Hemin-micelles exhibited excellent catalytic performance in the oxidation of phenolic and azo compounds by H2O2. In comparison with natural peroxidases, hemin-micelles have higher catalytic activity and better stability over wide temperature and pH ranges. Hemin-micelles can be used as a detection system for H2O2 with chromogenic substrates, and they anticipate the possibility of constructing new biocatalysts tailored to specific functions.
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Affiliation(s)
- Rui Qu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Functional Polymer Materials, Ministry of Education, Institute of Polymer Chemistry, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Nankai University , Tianjin 300071, China
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11
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Polyakov AY, Sorkina TA, Goldt AE, Pankratov DA, Perminova IV, Goodilin EA. Mössbauer spectroscopy of frozen solutions as a stepwise control tool in preparation of biocompatible humic-stabilized feroxyhyte nanoparticles. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s10751-013-0812-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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12
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Kuter D, Venter GA, Naidoo KJ, Egan TJ. Experimental and time-dependent density functional theory characterization of the UV-visible spectra of monomeric and μ-oxo dimeric ferriprotoporphyrin IX. Inorg Chem 2012; 51:10233-50. [PMID: 22963249 DOI: 10.1021/ic301154e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Speciation of ferriprotoporphyrin IX, Fe(III)PPIX, in aqueous solution is complex. Despite the use of its characteristic spectroscopic features for identification, the theoretical basis of the unique UV-visible absorbance spectrum of μ-[Fe(III)PPIX](2)O has not been explored. To investigate this and to establish a structural and spectroscopic model for Fe(III)PPIX species, density functional theory (DFT) calculations were undertaken for H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O. The models agreed with related Fe(III)porphyrin crystal structures and reproduced vibrational spectra well. The UV-visible absorbance spectra of H(2)O-Fe(III)PPIX and μ-[Fe(III)PPIX](2)O were calculated using time-dependent DFT and reproduced major features of the experimental spectra of both. Transitions contributing to calculated excitations have been identified. The features of the electronic spectrum calculated for μ-[Fe(III)PPIX](2)O were attributed to delocalization of electron density between the two porphyrin rings of the dimer, the weaker ligand field of the axial ligand, and antiferromagnetic coupling of the Fe(III) centers. Room temperature magnetic circular dichroism (MCD) spectra have been recorded and are shown to be useful in distinguishing between these two Fe(III)PPIX species. Bands underlying major spectroscopic features were identified through simultaneous deconvolution of UV-visible and MCD spectra. Computed UV-visible spectra were compared to deconvoluted spectra. Interpretation of the prominent bands of H(2)O-Fe(III)PPIX largely conforms to previous literature. Owing to the weak paramagnetism of μ-[Fe(III)PPIX](2)O at room temperature and the larger number of underlying excitations, interpretation of its experimental UV-visible spectrum was necessarily tentative. Nonetheless, comparison with the calculated spectra of antiferromagnetically coupled and paramagnetic forms of the μ-oxo dimer of Fe(III)porphine suggested that the composition of the Soret band involves a mixture of π→π* and π→d(π) charge transfer transitions. The Q-band and charge transfer bands appear to amalgamate into a mixed low energy envelope consisting of excitations with heavily admixed π→π* and charge transfer transitions.
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Affiliation(s)
- David Kuter
- Department of Chemistry, Department of Chemistry, University of Cape Town, Private Bag, Rondebosch 7701 South Africa
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13
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Wei J, Qiu J, Li L, Ren L, Zhang X, Chaudhuri J, Wang S. A reduced graphene oxide based electrochemical biosensor for tyrosine detection. NANOTECHNOLOGY 2012; 23:335707. [PMID: 22863907 DOI: 10.1088/0957-4484/23/33/335707] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this paper, a 'green' and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10(-7) M to 2 × 10(-5) M with a detection limitation of 7.5 × 10(-8) M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.
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Affiliation(s)
- Junhua Wei
- Department of Mechanical Engineering, Texas Tech University, 2500 Broadway, PO Box 41021, Lubbock, TX 79409-1021, USA
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Xue T, Jiang S, Qu Y, Su Q, Cheng R, Dubin S, Chiu CY, Kaner R, Huang Y, Duan X. Graphene-supported hemin as a highly active biomimetic oxidation catalyst. Angew Chem Int Ed Engl 2012; 51:3822-5. [PMID: 22368046 PMCID: PMC4249660 DOI: 10.1002/anie.201108400] [Citation(s) in RCA: 285] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/02/2012] [Indexed: 11/08/2022]
Abstract
Well supported: stable hemin-graphene conjugates formed by immobilization of monomeric hemin on graphene, showed excellent catalytic activity, more than 10 times better than that of the recently developed hemin-hydrogel system and 100 times better than that of unsupported hemin. The catalysts also showed excellent binding affinities and catalytic efficiencies approaching that of natural enzymes.
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Affiliation(s)
- Teng Xue
- Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, U. S. A
| | - Shan Jiang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A
| | - Yongquan Qu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A
| | - Qiao Su
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A
| | - Rui Cheng
- Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, U. S. A
| | - Sergey Dubin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A
| | - Chin-Yi Chiu
- Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, U. S. A
| | - Richard Kaner
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A.; California Nanosystems Institute, University of California, Los Angeles, CA 90095, U. S. A
| | - Yu Huang
- Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, U. S. A.; California Nanosystems Institute, University of California, Los Angeles, CA 90095, U. S. A
| | - Xiangfeng Duan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, U. S. A.; California Nanosystems Institute, University of California, Los Angeles, CA 90095, U. S. A
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15
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Xue T, Jiang S, Qu Y, Su Q, Cheng R, Dubin S, Chiu CY, Kaner R, Huang Y, Duan X. Graphene-Supported Hemin as a Highly Active Biomimetic Oxidation Catalyst. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108400] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Towards the conception of an amperometric sensor of l-tyrosine based on Hemin/PAMAM/MWCNT modified glassy carbon electrode. Electrochim Acta 2010. [DOI: 10.1016/j.electacta.2010.06.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Nhien NTT, Huy NT, Naito M, Oida T, Uyen DT, Huang M, Kikuchi M, Harada S, Nakayama K, Hirayama K, Kamei K. Neutralization of toxic haem by Porphyromonas gingivalis haemoglobin receptor. J Biochem 2009; 147:317-25. [PMID: 19861401 DOI: 10.1093/jb/mvp164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Free haem is known to be toxic to organs, tissues and cells. It enhances permeability by binding to a cell membrane, which leads to cell death, and damages lipids, proteins and DNA through the generation of reactive oxygen species. Lysine- and arginine-specific gingipains (Kgp and RgpA/B) are major proteinases that play an important role in the pathogenicity of a black-pigmented periodontopathogen named Porphyromonas gingivalis. One of the adhesin domains of gingipain, HbR could bind haem as an iron nutrient source for P. gingivalis. Using erythrocyte and its membrane as a model, results from the present study demonstrate that recombinant HbR expressed in Escherichia coli could inhibit haem-induced haemolysis, probably through removing haem from the haem-membrane complex and lowering free haem toxicity by mediating dimerization of haem molecules. The ability to protect a cell membrane from haem toxicity is a new function for HbR.
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Affiliation(s)
- Nguyen Thanh Thuy Nhien
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, Japan
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18
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Schwedhelm KF, Horstmann M, Faber JH, Reichert Y, Bringmann G, Faber C. The novel antimalarial compound dioncophylline C forms a complex with heme in solution. ChemMedChem 2008; 2:541-8. [PMID: 17315144 DOI: 10.1002/cmdc.200600263] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A structural model of the complex formed between the novel antimalarial compound dioncophylline C (DioC) and its presumed target ferriprotoporphyrin IX heme (FPIX) is presented. The complex structure was calculated with molecular dynamics (MD) simulations using intermolecular distance restraints between DioC and the iron center in FPIX, determined from NMR paramagnetic relaxation. Besides the spin state of the iron and longitudinal relaxation rates of hydrogen nuclei in DioC, the effective correlation time of paramagnetic relaxation was determined from NMR measurements at three different magnetic field strengths. The derived structural model shows high similarity to complexes formed by FPIX and antimalarials of the quinoline family (chloroquine, quinine, quinidine, and amodiaquine). The conformation of DioC is sterically stabilized by a water molecule coordinated to iron in FPIX. This structural feature may provide an important hint at possibilities for a further optimization of novel naphthylisoquinoline alkaloid (NIQ) antimalarial drugs.
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Affiliation(s)
- Kai F Schwedhelm
- Department of Experimental Physics 5, University of Würzburg, Am Hubland, 97074 Würzburg, Germany
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Wang Q, Yang Z, Zhang X, Xiao X, Chang CK, Xu B. A supramolecular-hydrogel-encapsulated hemin as an artificial enzyme to mimic peroxidase. Angew Chem Int Ed Engl 2007; 46:4285-9. [PMID: 17443763 DOI: 10.1002/anie.200700404] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Qigang Wang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, PR China
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20
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Smalley JW, Birss AJ, Szmigielski B, Potempa J. Sequential action of R- and K-specific gingipains of Porphyromonas gingivalis in the generation of the haem-containing pigment from oxyhaemoglobin. Arch Biochem Biophys 2007; 465:44-9. [PMID: 17577572 DOI: 10.1016/j.abb.2007.05.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 05/15/2007] [Accepted: 05/17/2007] [Indexed: 02/02/2023]
Abstract
The arginine- and lysine-specific gingipains of Porphyromonas gingivalis have been implicated in the degradation of haemoglobin from which the black mu-oxo haem dimer-containing pigment is generated. Here, we examined interactions of oxyhaemoglobin (oxyHb) with the Arg-(R)-specific (HRgpA) and Lys-(K)-specific (Kgp) gingipains. Incubation of oxyHb with HRgpA resulted in formation of methaemoglobin (metHb), which could be prevented by the R-gingipain specific inhibitor leupeptin. oxyHb-Kgp interactions resulted in formation of a haemoglobin haemichrome. This was inhibited by the lysine-specific protease inhibitor Z-Phe-Lys-acyloxymethylketone (Z-FKck). metHb, formed by treatment of oxyHb with either NaNO(2) or by pre-incubation with HRgpA, was rapidly degraded by Kgp compared to oxyHb. metHb degradation by Kgp was also inhibited Z-FKck. Together these data show that R-gingipain activity is crucial for converting oxyHb into the metHb form which is rendered more susceptible to Kgp degradation for the eventual release of iron(III) protoporphyrin IX and production of the mu-oxo haem dimer. This explains previous observations [J.W. Smalley, M.F. Thomas, A.J. Birss, R. Withnall, J. Silver, Biochem. J. 379 (2004) 833-840.] of the requirement for a combination of both R- and K-gingipains for pigment production from oxyhaemoglobin by P. gingivalis.
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Affiliation(s)
- John W Smalley
- Department of Clinical Dental Sciences, The University of Liverpool, Liverpool, UK.
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21
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Wang Q, Yang Z, Zhang X, Xiao X, Chang C, Xu B. A Supramolecular-Hydrogel-Encapsulated Hemin as an Artificial Enzyme to Mimic Peroxidase. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200700404] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Cowley AB, Benson DR. Weak-field anions displace the histidine ligand in a synthetic heme peptide but not in N-acetylmicroperoxidase-8: possible role of heme geometry differences. Inorg Chem 2007; 46:48-59. [PMID: 17198412 DOI: 10.1021/ic060682c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We have recently reported that aquo and thioether complexes of the ferric cytochrome c heme peptide N-acetylmicroperoxidase-8 (FeIII-1) exhibit greater low-spin character than do the corresponding complexes of a synthetic, water-soluble, monohistidine-ligated heme peptide (FeIII-2; Cowley, A. B.; Lukat-Rodgers, G. S.; Rodgers, K. R.; Benson, D. R. Biochemistry 2004, 43, 1656-1666). Herein we report results of studies showing that weak-field ligands bearing a full (fluoride, chloride, hydroxide) or partial (phenoxide, thiocyanate) negative charge on the coordinating atom trigger dissociation of the axial His ligand in FeIII-2 but not in FeIII-1. We attribute the greater sensitivity of His ligation in FeIII-1 to weak-field anionic ligands than to weak-field neutral ligands to the following phenomena: (1) anionic ligands pull FeIII further from the mean plane of a porphyrin than do neutral ligands, which will have the effect of straining the His-Fe bond in FeIII-2, and (2) heme in FeIII-2 is likely to undergo a modest doming distortion following anion binding that will render the His-ligated side of the porphyrin concave, thereby increasing porphyrin/ligand steric interactions. We propose that ruffling of the heme in FeIII-1 is an important factor contributing to its ability to resist His dissociation by weak-field anions. First, ruffling should allow His to more closely approach the porphyrin than is possible in FeIII-2, thereby reducing bond strain following anion binding. Second, the ruffling deformation in FeIII-1, which is enforced by the double covalent heme-peptide linkage, will almost certainly prevent significant porphyrin doming.
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Affiliation(s)
- Aaron B Cowley
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA
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23
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Olczak T, Simpson W, Liu X, Genco CA. Iron and heme utilization in Porphyromonas gingivalis. FEMS Microbiol Rev 2005; 29:119-44. [PMID: 15652979 DOI: 10.1016/j.femsre.2004.09.001] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 06/18/2004] [Accepted: 09/02/2004] [Indexed: 11/26/2022] Open
Abstract
Porphyromonas gingivalis is a Gram-negative anaerobic bacterium associated with the initiation and progression of adult periodontal disease. Iron is utilized by this pathogen in the form of heme and has been shown to play an essential role in its growth and virulence. Recently, considerable attention has been given to the characterization of various secreted and surface-associated proteins of P. gingivalis and their contribution to virulence. In particular, the properties of proteins involved in the uptake of iron and heme have been extensively studied. Unlike other Gram-negative bacteria, P. gingivalis does not produce siderophores. Instead it employs specific outer membrane receptors, proteases (particularly gingipains), and lipoproteins to acquire iron/heme. In this review, we will focus on the diverse mechanisms of iron and heme acquisition in P. gingivalis. Specific proteins involved in iron and heme capture will be described. In addition, we will discuss new genes for iron/heme utilization identified by nucleotide sequencing of the P. gingivalis W83 genome. Putative iron- and heme-responsive gene regulation in P. gingivalis will be discussed. We will also examine the significance of heme/hemoglobin acquisition for the virulence of this pathogen.
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Affiliation(s)
- Teresa Olczak
- Institute of Biochemistry and Molecular Biology, Laboratory of Biochemistry, Wroclaw University, Tamka 2, 50-137 Wroclaw, Poland.
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24
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Cornelius V, Snowden M, Silver J, Fern G. A study of the binding of the biologically important hematin molecule to a novel imidazole containing poly(N-isopropylacrylamide) microgel. REACT FUNCT POLYM 2004. [DOI: 10.1016/j.reactfunctpolym.2003.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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25
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Smalley JW, Silver J, Birss AJ, Withnall R, Titler PJ. The haem pigment of the oral anaerobes Prevotella nigrescens and Prevotella intermedia is composed of iron(III) protoporphyrin IX in the monomeric form. MICROBIOLOGY (READING, ENGLAND) 2003; 149:1711-1718. [PMID: 12855722 DOI: 10.1099/mic.0.26258-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The haem pigment of Porphyromonas gingivalis is composed of micro -oxo bishaem, [Fe(III)PPIX](2)O, but the nature of that generated by Prevotella species has not been established. Mössbauer, Raman and UV-visible spectrophotometry were used to characterize the haem pigment of Prevotella intermedia and Prevotella nigrescens. Mössbauer and Raman spectroscopy revealed the major haem species to be monomeric iron protoporphyrin IX, Fe(III)PPIX.OH (haematin). The terminal growth pH of both species on blood agar was between 5.8 and 6.0, which favours the formation and maintenance of monomeric Fe(III)PPIX.OH. Incubation of Pr. nigrescens and Pr. intermedia with oxyhaemoglobin at pH 6.5 resulted in formation of aquomethaemoglobin which was degraded to generate Fe(III)PPIX.OH which in turn became cell-associated, whilst incubation at pH 7.5 resulted in formation of [Fe(III)PPIX](2)O. It is concluded that both Prevotella species degrade oxyhaemoglobin to form [Fe(III)PPIX](2)O as an intermediate, which is converted to Fe(III)PPIX.OH through a depression in pH. The low pH encourages cell-surface deposition of insoluble Fe(III)PPIX.OH which would act as a barrier against oxygen and reactive oxygen species, and also protect against H(2)O(2) through its inherent catalase activity.
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Affiliation(s)
- John W Smalley
- Department of Clinical Dental Sciences, The University of Liverpool, Liverpool L69 3GN, UK
| | - Jack Silver
- School of Chemical and Life Sciences, The University of Greenwich, Chatham Maritime Campus, Pembroke, Chatham ME4 4TB, UK
| | - Andrew J Birss
- Department of Clinical Dental Sciences, The University of Liverpool, Liverpool L69 3GN, UK
| | - Robert Withnall
- School of Chemical and Life Sciences, The University of Greenwich, Chatham Maritime Campus, Pembroke, Chatham ME4 4TB, UK
| | - Philip J Titler
- School of Chemical and Life Sciences, The University of Greenwich, Chatham Maritime Campus, Pembroke, Chatham ME4 4TB, UK
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Smalley JW, Charalabous P, Hart CA, Silver J. Transmissible Burkholderia cepacia genomovar IIIa strains bind and convert monomeric iron(III) protoporphyrin IX into the mu-oxo oligomeric form. MICROBIOLOGY (READING, ENGLAND) 2003; 149:843-853. [PMID: 12686627 DOI: 10.1099/mic.0.26160-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia cepacia isolates of genomovar III are highly transmissible amongst patients with cystic fibrosis (CF) and express a 97 kDa putative haem-binding protein (HBP) [Smalley, J. W., Charalabous, P., Birss, A. J. & Hart, C. A. (2001). Clin Diagn Lab Immunol 8, 509-514]. An investigation of the interactions of iron(III) protoporphyrin IX with epidemic and non-epidemic strains of B. cepacia to determine the role of the above protein in haem acquisition and binding is reported herein. Spectrophotometric titrations of cell suspensions of genomovar IIIa strains BC7 and C5424 with iron(III) protoporphyrin IX, at pH 7.0, resulted in the depletion of Fe(III)PPIX.OH monomers and formation of the micro -oxo oligomeric species, [Fe(III)PPIX](2)O. Difference spectroscopy indicated a continuous conversion of the monomeric iron(III) protoporphyrin IX into micro -oxo oligomers. Incubations with Fe(III)PPIX.OH monomers at pH 6.5 also showed that cells could shift the equilibrium to generate the micro -oxo oligomeric form. Genomovar I strains ATCC 25416 and LMG 17997 were unable to mediate this conversion. SDS-PAGE of genomovar IIIa strains exposed to Fe(III)PPIX.OH at pH 6.5 followed by tetramethylbenzidine/H(2)O(2) staining revealed, in addition to the 97 kDa HBP, two proteins of 77 and 149 kDa located in the outer membrane which bound Fe(III)PPIX.OH monomers. These proteins were absent from the genomovar I strains. Genomovar IIIa strains BC7 and C5424 showed increased cellular binding of [Fe(III)PPIX](2)O, and as a consequence, displayed increased catalase activities compared to cells of the genomovar I isolates. It is concluded that, in addition to the putative 97 kDa HBP, B. cepacia genomovar IIIa strains express two outer-membrane proteins which function to bind and convert Fe(III)PPIX.OH monomers into the micro -oxo oligomeric form, [Fe(III)PPIX](2)O. The ability to perform this conversion at both neutral and slightly acidic pHs may enable epidemic strains to withstand attack from neutrophil-derived H(2)O(2) in the inflamed CF lung.
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Affiliation(s)
- John W Smalley
- Clinical Dental Science, University of Liverpool, Liverpool L69 3GN
| | | | - C Anthony Hart
- Department of Medical Microbiology and Genito-Urinary Medicine, University of Liverpool, Liverpool L69 3GN
| | - Jack Silver
- School of Chemical and Life Science, The University of Greenwich, Chatham Maritime Campus, Pembroke, Chatham ME4 4TB
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Smalley JW, Charalabous P, Birss AJ, Hart CA. Detection of heme-binding proteins in epidemic strains of Burkholderia cepacia. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2001; 8:509-14. [PMID: 11329449 PMCID: PMC96092 DOI: 10.1128/cdli.8.3.509-514.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A panel of 30 previously characterized strains representing five genomovars from the Burkholderia cepacia complex (E. Mahenthiralingam, T. Coenye, J. W. Chung, D. P. Speert, J. R. W. Govan, P. Taylor, and P. Vandamme, J. Clin. Microbiol. 38:910--913, 2000) were examined for their iron protoporphyrin IX-binding ability. These included B. cepacia genomovars I and III and B. stabilis (formerly B. cepacia genomovar IV), B. multivorans (formerly B. cepacia genomovar II), and B. vietnamiensis (formerly B. cepacia genomovar V). Cells were exposed to micro-oxo bisheme of iron protoporphyrin IX (micro-oxo dimers) and examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing, nondenaturing conditions for the presence of heme-binding proteins using tetramethylbenzidine-H(2)O(2) staining. Seven of the 30 strains, each belonging to B. cepacia genomovar III and designated epidemic (in possessing the B. cepacia epidemic strain marker), expressed a 96- to 100-kDa heme-binding protein which was located in the outer membrane. The heme-binding protein of B. cepacia genomovar III epidemic strain C5424 bound iron(III) protoporphyrin IX in both the monomeric and micro-oxo bisheme forms. Cells of all strains grown on Columbia agar bound iron protoporphyrin IX in the micro-oxo bisheme (dimeric) form. There were no statistical differences between the five genomovars, or those possessing the heme-binding protein, in their micro-oxo bisheme-binding ability. Possession of the outer membrane heme-binding protein may be a pathogenicity trait in enabling the bacterium to withstand oxidative stresses in inflammatory exudates in the lung and may aid identification of invasive epidemic strains of B. cepacia.
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Affiliation(s)
- J W Smalley
- Department of Clinical Dental Sciences, The University of Liverpool, Liverpool, United Kingdom.
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Parapini S, Basilico N, Pasini E, Egan TJ, Olliaro P, Taramelli D, Monti D. Standardization of the physicochemical parameters to assess in vitro the beta-hematin inhibitory activity of antimalarial drugs. Exp Parasitol 2000; 96:249-56. [PMID: 11162378 DOI: 10.1006/expr.2000.4583] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intraerythrocytic plasmodia form hemozoin as a detoxification product of hemoglobin-derived heme. An identical substance, beta-hematin (BH), can be obtained in vitro from hematin at acidic pH. Quinoline-antimalarials inhibit BH formation. Standardization of test conditions is essential for studying the interaction of compounds with this process and screening potential inhibitors. A spectrophotometric microassay of heme polymerization inhibitory activity (HPIA) (Basilico et al., Journal of Antimicrobial Chemotherapy 42, 55-60, 1998) previously reported was used to investigate the effect of pH and salt concentration on BH formation. The yield of BH formation decreased with pH. Moreover, under conditions used in the above HPIA assay (18 h, 37 degrees C, pH = 2.7), several salts including chloride and phosphate inhibited the process. Aminoquinoline drugs formulated as salts (chloroquine-phosphate, primaquine-diphosphate), but not chloroquine-base, also inhibited the reaction. Interference by salts was highest at low pH and decreased at higher pH (pH 4). Here, we describe different assay conditions that eliminate these problems (BHIA, beta-hematin inhibitory activity). By replacing hematin with hemin as the porphyrin and NaOH solution with DMSO as solvent, the formation of BH was independent of pH up to pH 5.1. No interference by salts was observed over the pH range 2.7-5.1. Dose-dependent inhibition of BH formation was obtained with chloroquine-base, chloroquine-phosphate, and chloroquine-sulfate at pH 5.1. Primaquine was not inhibitory. The final product, characterized by solubility in DMSO, consists of pure BH by FT-IR spectroscopy. The BHIA assay (hemin in DMSO, acetate buffer pH 5 +/- 0.1, 18 h at 37 degrees C) is designed to screen for those molecules forming pi-pi interactions with hematin and thus inhibiting beta-hematin formation.
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Affiliation(s)
- S Parapini
- Istituto di Microbiologia, Universitá di Milano, Via Pascal 36, 20133 Milano, Italy
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Smalley JW, Birss AJ, Silver J. The periodontal pathogen Porphyromonas gingivalis harnesses the chemistry of the mu-oxo bishaem of iron protoporphyrin IX to protect against hydrogen peroxide. FEMS Microbiol Lett 2000; 183:159-64. [PMID: 10650220 DOI: 10.1111/j.1574-6968.2000.tb08951.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The major haem component in the black pigment of Porphyromonas gingivalis is the mu-oxo bishaem of iron protoporphyrin IX and formation and cell-surface binding of this haem species is proposed as an extracellular buffer against reactive oxidants [Smalley, J.W. et al. (1998) Biochem. J. 331, 681-685]. P. gingivalis cells grown in the presence of the mu-oxo bishaem were protected against H(2)O(2) compared to control cells grown without it. When added to the growth medium, soluble mu-oxo bishaem inactivated H(2)O(2) and supported cell growth. Cells carrying a surface layer of mu-oxo bishaem were less susceptible to peroxidation by H(2)O(2). Cell-surface haems were slowly destroyed during reaction with H(2)O(2). Binding of mu-oxo bishaem by P. gingivalis may aid survival during neutrophil attack through inactivation of hydrogen peroxide.
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Affiliation(s)
- J W Smalley
- Unit of Oral Biology, The Edwards Building, Department of Clinical Dental Sciences, The University of Liverpool, Liverpool, UK.
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Vippagunta SR, Dorn A, Matile H, Bhattacharjee AK, Karle JM, Ellis WY, Ridley RG, Vennerstrom JL. Structural specificity of chloroquine-hematin binding related to inhibition of hematin polymerization and parasite growth. J Med Chem 1999; 42:4630-9. [PMID: 10579825 DOI: 10.1021/jm9902180] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Considerable data now support the hypothesis that chloroquine (CQ)-hematin binding in the parasite food vacuole leads to inhibition of hematin polymerization and parasite death by hematin poisoning. To better understand the structural specificity of CQ-hematin binding, 13 CQ analogues were chosen and their hematin binding affinity, inhibition of hematin polymerization, and inhibition of parasite growth were measured. As determined by isothermal titration calorimetry (ITC), the stoichiometry data and exothermic binding enthalpies indicated that, like CQ, these analogues bind to two or more hematin mu-oxo dimers in a cofacial pi-pi sandwich-type complex. Association constants (K(a)'s) ranged from 0.46 to 2.9 x 10(5) M(-1) compared to 4.0 x 10(5) M(-1) for CQ. Remarkably, we were not able to measure any significant interaction between hematin mu-oxo dimer and 11, the 6-chloro analogue of CQ. This result indicates that the 7-chloro substituent in CQ is a critical structural determinant in its binding affinity to hematin mu-oxo dimer. Molecular modeling experiments reinforce the view that the enthalpically favorable pi-pi interaction observed in the CQ-hematin mu-oxo dimer complex derives from a favorable alignment of the out-of-plane pi-electron density in CQ and hematin mu-oxo dimer at the points of intermolecular contact. For 4-aminoquinolines related to CQ, our data suggest that electron-withdrawing functional groups at the 7-position of the quinoline ring are required for activity against both hematin polymerization and parasite growth and that chlorine substitution at position 7 is optimal. Our results also confirm that the CQ diaminoalkyl side chain, especially the aliphatic tertiary nitrogen atom, is an important structural determinant in CQ drug resistance. For CQ analogues 1-13, the lack of correlation between K(a) and hematin polymerization IC(50) values suggests that other properties of the CQ-hematin mu-oxo dimer complex, rather than its association constant alone, play a role in the inhibition of hematin polymerization. However, there was a modest correlation between inhibition of hematin polymerization and inhibition of parasite growth when hematin polymerization IC(50) values were normalized for hematin mu-oxo dimer binding affinities, adding further evidence that antimalarial 4-aminoquinolines act by this mechanism.
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Affiliation(s)
- S R Vippagunta
- College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, USA
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Bauminger ER, Treffry A, Quail MA, Zhao Z, Nowik I, Harrison PM. Stages in iron storage in the ferritin of Escherichia coli (EcFtnA): analysis of Mössbauer spectra reveals a new intermediate. Biochemistry 1999; 38:7791-802. [PMID: 10387019 DOI: 10.1021/bi990377l] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Iron uptake into the nonheme ferritin of Escherichia coli (EcFtnA) and its site-directed variants have been investigated by Mössbauer spectroscopy. EcFtnA, like recombinant human H chain ferritin (HuHF), oxidized Fe(II) at a dinuclear ferroxidase center situated at a central position within each subunit. As with HuHF, Mössbauer subspectra observed between 1 min and 24 h after Fe(II) addition were assigned to Fe(III) monomers, "c", mu-oxo-bridged dimers, "b", and clusters, "a", the latter showing magnetically split spectra, "d", at 4.1 K. Like those of HuHF, the mu-oxo-bridged dimers were formed at the ferroxidase centers. However, the analysis also revealed the presence of a new type of dimer, "e" (QS1 = 0.38 mm/s, IS1 = 0.51 mm/s and QS2 = 0.72 mm/s, IS2 = 0.50 mm/s), and this was also assigned to the ferroxidase center. Dimers "b" appeared to be converted to dimers "e" over time. Subspectra "e" became markedly asymmetric at temperatures above 90 K, suggesting that the two Fe(III) atoms of dimers "e" were more weakly coupled than in the mu-oxo-bridged dimers "b", possibly due to OH- bridging. Monomeric Fe(III), giving relaxation spectra "c", was assigned to a unique site C that is near the dinuclear center. In EcFtnA all three iron atoms seemed to be oxidized together. In contrast to HuHF, no Fe(III) clusters were observed 24 h after the aerobic addition of 48 Fe(II) atoms/molecule in wild-type EcFtnA. This implies that iron is more evenly distributed between molecules in the bacterial ferritins, which may account for its greater accessibility.
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Affiliation(s)
- E R Bauminger
- Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
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Egan TJ, Hempelmann E, Mavuso WW. Characterisation of synthetic beta-haematin and effects of the antimalarial drugs quinidine, halofantrine, desbutylhalofantrine and mefloquine on its formation. J Inorg Biochem 1999; 73:101-7. [PMID: 10212997 DOI: 10.1016/s0162-0134(98)10095-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Infrared spectroscopy, elemental analysis and X-ray powder diffraction show that the product of 30 min of reaction of haematin in 4.5 M acetate, pH 4.5 at 60 degrees C is identical to beta-haematin prepared in 4.5 M acetic acid at 70 degrees C overnight (pH 2.6). There is no evidence for formation of haem-acetate complex, which could not be isolated, even from 11.4 M acetate solution. The antimalarial drugs quinidine, halofantrine, desbutylhalofantrine and mefloquine were found to inhibit formation of beta-haematin, while 5-, 6- and 8-aminoquinoline and quinoline were found to have no effect. Quinidine was shown to form a complex with ferriprotoporphyrin IX in 40% DMSO with log K = 5.02 +/- 0.03. Log K values for halofantrine and desbutylhalofantrine are 5.29 +/- 0.02 and 5.15 +/- 0.02 respectively (solutions containing 30% acetonitrile in addition to DMSO to solubilise these drugs), which are both stronger than chloroquine under the same conditions (log K = 4.56 +/- 0.02).
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Affiliation(s)
- T J Egan
- Department of Chemistry, University of Cape Town, Rondebosch, South Africa.
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Dorn A, Vippagunta SR, Matile H, Jaquet C, Vennerstrom JL, Ridley RG. An assessment of drug-haematin binding as a mechanism for inhibition of haematin polymerisation by quinoline antimalarials. Biochem Pharmacol 1998; 55:727-36. [PMID: 9586944 DOI: 10.1016/s0006-2952(97)00510-8] [Citation(s) in RCA: 220] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chloroquine is thought to exert its antimalarial activity by preventing the polymerisation of toxic haematin released during proteolysis of haemoglobin in the Plasmodium digestive vacuole. However, the molecular mechanisms by which this inhibition occurs and the universality of this mechanism for other quinoline antimalarials remain to be established. We demonstrate here a correlation for eight antimalarial quinolines between inhibition of haematin polymerisation in vitro and inhibition of P. falciparum growth in culture, confirming haematin polymerisation as the likely target of quinoline blood schizonticides. Furthermore, using isothermal titration microcalorimetry, a correlation was observed between the haematin binding constant of these compounds and their ability to inhibit haematin polymerisation, suggesting that these compounds mediate their activity through binding to haematin. It was also observed that the compounds bind primarily to the mu-oxo dimer form of haematin rather than the monomeric form. It is postulated that this binding inhibits haematin polymerisation by shifting the haematin dimerisation equilibrium to the mu-oxo dimer, thus reducing the availability of monomeric haematin for incorporation into haemozoin. These data reconcile the haematin polymerisation theory with the Fitch hypothesis, which states that chloroquine mediates its activity through binding to haematin.
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Affiliation(s)
- A Dorn
- Pharma Division, Preclinical Research, F. Hoffmann-La Roche Ltd, Basel, Switzerland
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Pilloud DL, Rabanal F, Gibney BR, Farid RS, Dutton PL, Moser CC. Self-Assembled Monolayers of Synthetic Hemoproteins on Silanized Quartz. J Phys Chem B 1998. [DOI: 10.1021/jp973348y] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Denis L. Pilloud
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Francesc Rabanal
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Brian R. Gibney
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Ramy S. Farid
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - P. Leslie Dutton
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Christopher C. Moser
- The Johnson Research Foundation, Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Adams PA, Berman PA, Egan TJ, Marsh PJ, Silver J. The iron environment in heme and heme-antimalarial complexes of pharmacological interest. J Inorg Biochem 1996; 63:69-77. [PMID: 8699174 DOI: 10.1016/0162-0134(95)00212-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Mössbauer spectroscopy has been utilized to probe the electronic environment of iron in a number of Ferriprotoporphyrin IX complexes of relevance to malaria. The markedly different iron environments found for the complexes of hemin with quinine, chloroquine, and the Chinese herbal antimalarial artesunate suggest that these compounds act by protecting the heme from polymerization to insoluble hemozoin, and by facilitating the transport of the protected heme to the food vacuole membrane where it is able to exercise its cytotoxic redox catalytic activity. Mössbauer parameters determined here for purified malaria pigment and synthetic beta-hematin confirm the chemical identical-ness of these species. The Mössbauer spectra of the complexes are discussed in light of the proposed structures of the complexes.
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Affiliation(s)
- P A Adams
- Department of Clinical Pathology, University of Cape Town Medical School, Cape Town, South Africa
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Marsh PJ, Silver J, Symons MCR, Taiwo FA. Mössbauer and electron paramagnetic resonance studies on some new bis-(ligated) porphyrinatoiron(III) complexes with aliphatic amines. Models for cytochromes b. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/dt9960002361] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Macrophage nitric oxide synthase subunits. Purification, characterization, and role of prosthetic groups and substrate in regulating their association into a dimeric enzyme. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36901-7] [Citation(s) in RCA: 289] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values part II. Aliphatic nitrogen ligands. Inorganica Chim Acta 1991. [DOI: 10.1016/s0020-1693(00)82993-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values. Part I. Pyridine and imidazole ligands. Inorganica Chim Acta 1990. [DOI: 10.1016/s0020-1693(00)84861-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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A Mössbauer study on the (protoporphyrinato IX)iron(II) complexes of imidazole and substituted imidazoles as axial ligands in frozen aqueous solutions. Inorganica Chim Acta 1989. [DOI: 10.1016/s0020-1693(00)80797-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Medhi OK, Silver J. Mössbauer spectroscopic evidence for molecular complex formation between histidine and μ-oxo-bis(protoporphyrinato IX)iron(III). Inorganica Chim Acta 1989. [DOI: 10.1016/s0020-1693(00)83227-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abu-Soud HM, Silver J. Mössbauer spectroscopic studies on short ‘self-fenced’ porphyrinato iron(III) complexes. Evidence for the absence of μ-oxo-bridged formation. Inorganica Chim Acta 1989. [DOI: 10.1016/s0020-1693(00)80883-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Medhi O, Houlton A, Silver J. A six-coordinate high spin protoporphyrin IX iron(III) complex as a model for ferric haemproteins: Mössbauer spectrum of bisaquo(protoporphyrinato IX)iron(III) encapsulated in aqueous detergent micelles. Inorganica Chim Acta 1989. [DOI: 10.1016/s0020-1693(00)83095-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Silver J, Taies JA. Model complexes for the high spin iron(II) state in the catalytic cycle of cytochrome P450. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)88874-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Towards an understanding of the quadrupole splittings found in the Mössbauer spectroscopic data of a number of substituted tetraphenylporphyriniron(III) halides. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)86305-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Medhi OK, Silver J. On the nature of protoporphyrin(IX) iron(III) in aqueous solution at and below the pH of precipitation. Inorganica Chim Acta 1988. [DOI: 10.1016/s0020-1693(00)86302-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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