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Silver J, al-Jaff G, Taies JA, Wilson MT, den Engelsen D, Fern GR, Ireland TG. Studies on the binding of CO to low-spin [Fe(II)(Por)L 2] complexes: an aid to understanding the binding of CO to haemoglobin and myoglobin. J Biol Inorg Chem 2023; 28:65-84. [PMID: 36478266 PMCID: PMC9938061 DOI: 10.1007/s00775-022-01969-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 10/13/2022] [Indexed: 12/12/2022]
Abstract
The visible and Mössbauer spectra of [Fe(II)(Por)L2] and [Fe(II)(Por)L(CO)] complexes (where Por = protoporphyrin IX (PPIX) or tetra(p-sulfophenyl)porphyrin (TPPS) and L = an aliphatic or aromatic nitrogenous base) are reported and discussed. The results are compared to those of previously reported [Fe(II)(Por)L(CO)] complexes (where Por = PPIX, TPPS, PMXPP, TPP, OMTBP and OEP; L = a nitrogenous aromatic ligand) and HbCO (where Hb = haemoglobin) and MyCO (where My = myoglobin). A new approach, to extracting information from the Mössbauer parameters has been developed by plotting those of the [Fe(II)(Por)L2] complexes against those of [Fe(II)(Por)L(CO)] complexes for the same ligands, has yielded a series of trend lines that show a significant dependence on both the nature of the porphyrin and also of the nitrogenous ligand. Different trend lines were found for aromatic nitrogenous ligands to aliphatic nitrogenous ligands showing that the porphyrins could donate different amounts of charge to the Fe(II) cations as the L ligand changed, and hence, they display electron sink properties. From the plots, it was shown that haemoglobin and myoglobin both bind CO very strongly compared to the model complexes studied herein. Using the reported structural and Mössbauer data for the [Fe(II)(Por)L2] and [Fe(II)(Por)L(CO)] complexes, it proved possible and instructive to plot the Mössbauer parameters against a number of the bond lengths around the Fe(II) cations. The interpretation of the resulting trend lines both supported and facilitated the extension of our findings enabling further understanding of the geometry of the bonding in CO haemoglobin and CO myoglobin.
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Affiliation(s)
- Jack Silver
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - Golzar al-Jaff
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK ,grid.444950.8Department of Chemistry, College of Education, Salahaddin University-Erbil, Erbil, Iraq
| | - Jehad A. Taies
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK ,Department of Chemistry, College of Education for Pure Science, University of Anwar, Ramadi, Iraq
| | - Michael T. Wilson
- grid.8356.80000 0001 0942 6946School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ Essex UK
| | - Daniel den Engelsen
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - George R. Fern
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
| | - Terry G. Ireland
- grid.7728.a0000 0001 0724 6933College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH Middlesex UK
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Silver J, Al-Jaff G, Wilson MT, den Engelsen D, Fern GR, Ireland TG. Studies on the binding of nitrogenous bases to protoporphyrin IX iron(II) in aqueous solution at high pH values. J Biol Inorg Chem 2022; 27:297-313. [PMID: 35235042 PMCID: PMC8960585 DOI: 10.1007/s00775-022-01929-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/14/2022] [Indexed: 10/28/2022]
Abstract
Studies are reported on the formation of low-spin six-coordinate [Fe(PPIX)L2] complexes from iron(II) protoporphyrin where L is one of a series of nitrogenous ligands (aliphatic, aromatic or heterocyclic). The bonding constants have been determined by titration of the metal complex with these ligands and are compared in relation to previous studies. The adduct formation was monitored utilising optical spectroscopy. In addition, Mӧssbauer spectroscopic experiments were conducted to monitor the electronic environment around the central iron atom in these complexes. The two complementary spectroscopic methods indicated that all nitrogen ligands formed low-spin octahedral complexes. The magnitude of the overall binding constants (β2 values) are discussed and related to (a) the pKa values of the free ligands and (b) the Mössbauer parameter ΔEQ, which represents the quadrupole splitting of the haem iron. The β2 and ΔEQ values are also discussed in terms of the structure of the ligand. Cooperative binding was observed for nearly all the ligands with Hill coefficients close to 2 for iron(II) protoporphyrin; one of these ligands displayed a much greater affinity than any we previously studied, and this was a direct consequence of the structure of the ligand. Overall conclusions on these and previous studies are drawn in terms of aliphatic ligands versus aromatic ring structures and the absence or presence of sterically hindered nitrogen atoms. The implications of the work for the greater understanding of haem proteins in general and in particular how the nitrogenous ligand binding results are relevant to and aid the understanding of the binding of inhibitor molecules to the cytochrome P450 mono-oxygenases (for therapeutic purposes) are also discussed. Changes in the electronic absorption spectra of five-coordinate [Fe(II)(PPIX)(2-MeIm)] that occurred as the temperature was lowered from room temperature to 78° K.
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Affiliation(s)
- Jack Silver
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - Golzar Al-Jaff
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK.,Department of Chemistry, College of Education, Salahaddin University-Erbil, Erbil, Iraq
| | - Michael T Wilson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, Essex, UK
| | - Daniel den Engelsen
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - George R Fern
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK
| | - Terry G Ireland
- College of Engineering, Design and Physical Sciences, School of Engineering, Wolfson Centre for Materials Processing, Brunel University London, Kingston Lane, Uxbridge, UB8 3PH, Middlesex, UK.
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Ferentinos E, Chatziefthimiou S, Boudalis AK, Pissas M, Mathies G, Gast P, Groenen EJJ, Sanakis Y, Kyritsis P. The [Fe{(SePPh2
)2
N}2
] Complex Revisited: X-ray Crystallography, Magnetometry, High-Frequency EPR, and Mössbauer Studies Reveal Its Tetrahedral FeII
Se4
Coordination Sphere. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201701459] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Eleftherios Ferentinos
- Inorganic Chemistry Laboratory; Department of Chemistry; National and Kapodistrian University of Athens; Panepistimiopolis 15771 Athens Greece
| | - Spyros Chatziefthimiou
- Institute of Nanoscience and Nanotechnology; N.C.S.R. “Demokritos”; Aghia Paraskevi 15310 Attiki Greece
| | - Athanassios K. Boudalis
- Institute of Nanoscience and Nanotechnology; N.C.S.R. “Demokritos”; Aghia Paraskevi 15310 Attiki Greece
| | - Michael Pissas
- Institute of Nanoscience and Nanotechnology; N.C.S.R. “Demokritos”; Aghia Paraskevi 15310 Attiki Greece
| | - Guinevere Mathies
- Huygens-Kamerlingh Onnes Laboratory; Department of Physics; Leiden University; Niels Bohrweg 2 2333 CA Leiden The Netherlands
| | - Peter Gast
- Huygens-Kamerlingh Onnes Laboratory; Department of Physics; Leiden University; Niels Bohrweg 2 2333 CA Leiden The Netherlands
| | - Edgar J. J. Groenen
- Huygens-Kamerlingh Onnes Laboratory; Department of Physics; Leiden University; Niels Bohrweg 2 2333 CA Leiden The Netherlands
| | - Yiannis Sanakis
- Institute of Nanoscience and Nanotechnology; N.C.S.R. “Demokritos”; Aghia Paraskevi 15310 Attiki Greece
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory; Department of Chemistry; National and Kapodistrian University of Athens; Panepistimiopolis 15771 Athens Greece
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Rebouças JS, James BR. Molecular Recognition Using Ruthenium(II) Porphyrin Thiol Complexes as Probes. Inorg Chem 2013; 52:1084-98. [DOI: 10.1021/ic302401m] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Júlio S. Rebouças
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, PB 58.051-900,
Brazil
| | - Brian R. James
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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Vashi PR, Marques HM. The coordination of imidazole and substituted pyridines by the hemeoctapeptide N-acetyl-ferromicroperoxidase-8 (FeIINAcMP8). J Inorg Biochem 2005; 98:1471-82. [PMID: 15337599 DOI: 10.1016/j.jinorgbio.2004.05.016] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2004] [Revised: 05/11/2004] [Accepted: 05/18/2004] [Indexed: 11/23/2022]
Abstract
The N-terminus acetylated ferric hemeoctapeptide from cytochrome c, N-acetylmicroperoxidase-8 (Fe(III)-NAcMP8) can be reduced by dithionite in aqueous solution to produce Fe(II)-NAcMP8. The UV-Vis spectrum has a broad Soret band and relatively poorly defined Q bands which is consistent with a mixture of a five-coordinate high spin species with His as the axial ligand and a six-coordinate, predominantly high spin species with His/H(2)O as axial ligands. There are two spectroscopically observable pK(a)s at 8.7+/-0.1 and 10.9+/-0.2 which are attributed to ionization of a heme propionic acid group and coordinated H(2)O, respectively; a pK(a) > or = 14 is due to ionization of the proximal His ligand. Equilibrium constants were determined by UV-Vis spectrophotometry at 25.0+/-0.2 degrees C and 0.5 M ionic strength (NaClO(4)) for the coordination of imidazole and a number of substituted pyridines, and complement available data for the ferric hemepeptide, allowing a comparison to be made of the affinity of an iron porphyrin with Fe in the +2 and +3 oxidation states towards these ligands. Imidazole is coordinated more strongly by the ferric porphyrin (log K=4.08) than by the ferrous porphyrin (log K=3.40). The equilibrium constants for coordination of pyridines by the ferric and ferrous porphyrins increase and decrease, respectively, with increasing ligand basicity. Values determined by cyclic voltammetry show the same dependence on the identity of the ligand. In the ferric porphyrin, the stability of the complex increases with the basicity of the ligand and hence its ability to donate electron density onto the metal. In the case of the more electron rich ferrous porphyrin, greater stability occurs with pyridine ligands that have an electron withdrawing group and hence can accept electron density from the metal. This is consistent with the midpoint reduction potentials E(1/2) of the pyridine complexes determined by cyclic voltammetry; E(1/2) is linearly dependent on, and becomes more negative with an increase in, ligand basicity. Log K for coordination of pyridines by the ferrous hemepeptide correlates well with the energy of the ligand frontier orbital with pi symmetry, suggesting that pi-bonding effects are significant in determining the strength of binding of pyridines by a ferrous porphyrin.
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Affiliation(s)
- Preeti R Vashi
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, P.O. Wits, Johannesburg 2050, South Africa
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Walker FA. Models of the Bis-Histidine-Ligated Electron-Transferring Cytochromes. Comparative Geometric and Electronic Structure of Low-Spin Ferro- and Ferrihemes. Chem Rev 2004; 104:589-615. [PMID: 14871136 DOI: 10.1021/cr020634j] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F Ann Walker
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721-0041, USA.
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Safo MK, Nesset MJM, Walker FA, Debrunner PG, Scheidt WR. Models of the Cytochromes. Axial Ligand Orientation and Complex Stability in Iron(II) Porphyrinates: The Case of the Noninteracting dπ Orbitals. J Am Chem Soc 1997. [DOI: 10.1021/ja9715657] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Martin K. Safo
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - Marlys J. M. Nesset
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - F. Ann Walker
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - Peter G. Debrunner
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
| | - W. Robert Scheidt
- Contribution from the Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, Department of Chemistry, University of Arizona, Tucson, Arizona 85721, and Department of Physics, University of Illinois, Urbana, Illinois 61801
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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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9
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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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10
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Mössbauer spectroscopic studies on the bis(histidine) adducts of (protoporphyrinato IX)iron(II). Inorganica Chim Acta 1990. [DOI: 10.1016/s0020-1693(00)80954-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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