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Jacobs FJ, Helliwell JR, Brink A. Time-series analysis of rhenium(I) organometallic covalent binding to a model protein for drug development. IUCRJ 2024; 11:359-373. [PMID: 38639558 PMCID: PMC11067751 DOI: 10.1107/s2052252524002598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 03/19/2024] [Indexed: 04/20/2024]
Abstract
Metal-based complexes with their unique chemical properties, including multiple oxidation states, radio-nuclear capabilities and various coordination geometries yield value as potential pharmaceuticals. Understanding the interactions between metals and biological systems will prove key for site-specific coordination of new metal-based lead compounds. This study merges the concepts of target coordination with fragment-based drug methodologies, supported by varying the anomalous scattering of rhenium along with infrared spectroscopy, and has identified rhenium metal sites bound covalently with two amino acid types within the model protein. A time-based series of lysozyme-rhenium-imidazole (HEWL-Re-Imi) crystals was analysed systematically over a span of 38 weeks. The main rhenium covalent coordination is observed at His15, Asp101 and Asp119. Weak (i.e. noncovalent) interactions are observed at other aspartic, asparagine, proline, tyrosine and tryptophan side chains. Detailed bond distance comparisons, including precision estimates, are reported, utilizing the diffraction precision index supplemented with small-molecule data from the Cambridge Structural Database. Key findings include changes in the protein structure induced at the rhenium metal binding site, not observed in similar metal-free structures. The binding sites are typically found along the solvent-channel-accessible protein surface. The three primary covalent metal binding sites are consistent throughout the time series, whereas binding to neighbouring amino acid residues changes through the time series. Co-crystallization was used, consistently yielding crystals four days after setup. After crystal formation, soaking of the compound into the crystal over 38 weeks is continued and explains these structural adjustments. It is the covalent bond stability at the three sites, their proximity to the solvent channel and the movement of residues to accommodate the metal that are important, and may prove useful for future radiopharmaceutical development including target modification.
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Affiliation(s)
- Francois J.F. Jacobs
- Department of Chemistry, University of the Free State, Nelson Mandela Drive, Bloemfontein, 9301, South Africa
| | - John R. Helliwell
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
| | - Alice Brink
- Department of Chemistry, University of the Free State, Nelson Mandela Drive, Bloemfontein, 9301, South Africa
- Department of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
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Brink A, Jacobs FJF, Helliwell JR. Trends in coordination of rhenium organometallic complexes in the Protein Data Bank. IUCRJ 2022; 9:180-193. [PMID: 35371500 PMCID: PMC8895017 DOI: 10.1107/s2052252522000665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Radiopharmaceutical development has similar overall characteristics to any biomedical drug development requiring a compound's stability, aqueous solubility and selectivity to a specific disease site. However, organometallic complexes containing 188/186Re or 99mTc involve a d-block transition-metal radioactive isotope and therefore bring additional factors such as metal oxidation states, isotope purity and half life into play. This topical review is focused on the development of radiopharmaceuticals containing the radioisotopes of rhenium and technetium and, therefore, on the occurrence of these organometallic complexes in protein structures in the Worldwide Protein Data Bank (wwPDB). The purpose of incorporating the group 7 transition metals of rhenium/technetium in the protein and the reasons for study by protein crystallography are described, as certain PDB studies were not aimed at drug development. Technetium is used as a medical diagnostic agent and involves the 99mTc isotope which decays to release gamma radiation, thereby employed for its use in gamma imaging. Due to the periodic relationship among group 7 transition metals, the coordination chemistry of rhenium is similar (but not identical) to that of technetium. The types of reactions the potential model radiopharmaceutical would prefer to partake in, and by extension knowing which proteins and biomolecules the compound would react with in vivo, are needed. Crystallography studies, both small molecule and macromolecular, are a key aspect in understanding chemical coordination. Analyses of bonding modes, coordination to particular residues and crystallization conditions are presented. In our Forward look as a concluding summary of this topical review, the question we ask is: what is the best way for this field to progress?
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Affiliation(s)
- Alice Brink
- Chemistry Department, University of the Free State, Nelson Mandela Drive, Bloemfontein, South Africa
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom
| | - Francois J. F. Jacobs
- Chemistry Department, University of the Free State, Nelson Mandela Drive, Bloemfontein, South Africa
| | - John R. Helliwell
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom
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Loreto D, Esposito A, Demitri N, Guaragna A, Merlino A. Reactivity of a fluorine-containing dirhodium tetracarboxylate compound with proteins. Dalton Trans 2022; 51:3695-3705. [PMID: 35166290 DOI: 10.1039/d2dt00082b] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dirhodium complexes of general formula [Rh2(O2CR)4]L2 are a well-known class of bimetallic compounds that are used as efficient catalysts for a variety of reactions and have been shown to be potent antibacterial and anticancer agents. The catalytic and biological properties of these complexes largely depend on the nature of the bridging carboxylate ligands. Trifluoroacetate (tfa)-containing dirhodium compounds have been used to build artificial metalloenzymes upon reaction with peptides and have been shown to be more cytotoxic than dirhodium tetraacetate. However, there is no structural information on the interaction between these compounds and proteins. Here, cis-Rh2(μ-O2CCH3)2(μ-O2CCF3)2 ([cis-Rh2(OAc)2(tfa)2]) has been synthesized and its reaction with bovine pancreatic ribonuclease (RNase A) and hen egg white lysozyme (HEWL) was analyzed using a combination of different techniques, including Fluorine-19 nuclear magnetic resonance spectroscopy and macromolecular X-ray crystallography, with the aim to unveil the differences in the reactivity of tfa-containing dihrodium complexes with proteins when compared to [Rh2(OAc)4]. [cis-Rh2(OAc)2(tfa)2] and [Rh2(OAc)4] bind the N atoms of His side chains of RNase A at the axial position; however the fluorine-containing compound rapidly loses its tfa ligands, while [Rh2(OAc)4] can retain the acetate ligands upon protein binding. The reactivity of [cis-Rh2(OAc)2(tfa)2] with HEWL is slightly distinct when compared to that of [Rh2(OAc)4] under the same experimental conditions; however, both [cis-Rh2(OAc)2(tfa)2] and [Rh2(OAc)4] degrade when soaked within HEWL crystals. These results provide a structural-based guide for the design of new heterogenous chiral dirhodium/peptide and dirhodium/protein adducts with application in the fields of organic synthesis and asymmetric catalysis.
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Affiliation(s)
- Domenico Loreto
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, via Cinthia 21, 80126 Naples, Italy.
| | - Anna Esposito
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, P.le V. Tecchio 80, 80125 Naples, Italy
| | - Nicola Demitri
- Elettra-Sincrotrone Trieste, S.S. 14 km 163.5 in Area Science Park, 34149 Trieste, Italy
| | - Annalisa Guaragna
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II, P.le V. Tecchio 80, 80125 Naples, Italy
| | - Antonello Merlino
- Department of Chemical Sciences, University of Naples Federico II, Complesso Universitario di Monte Sant'Angelo, via Cinthia 21, 80126 Naples, Italy.
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Loreto D, Esposito A, Demitri N, Guaragna A, Merlino A. Digging into protein metalation differences triggered by fluorine containing-dirhodium tetracarboxylate analogues. Dalton Trans 2022; 51:7294-7304. [DOI: 10.1039/d2dt00873d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic and biological properties of dirhodium tetracarboxylates ([Rh2(μ-O2CR)4L2], L=axial ligand, R=CH3-, CH3CH2-, etc) largely depend on the nature of the bridging carboxylate equatorial μ-O2CR ligands, which can be easily exchanged...
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Helliwell JR. Pre- and Post-publication Verification for Reproducible Data Mining in Macromolecular Crystallography. Methods Mol Biol 2022; 2449:235-261. [PMID: 35507266 DOI: 10.1007/978-1-0716-2095-3_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Like an article narrative is deemed by an editor and referees to be worthy of being a version of record on acceptance as a publication, so must the underpinning data also be scrutinized before passing it as a version of record. Indeed without the underpinning data, a study and its conclusions cannot be reproduced at any stage of evaluation, pre- or post-publication. Likewise, an independent study without its own underpinning data also cannot be reproduced let alone be considered a replicate of the first study. The PDB is a modern marvel of achievement providing an organized open access to depositor and user of the data held there opening numerous applications. Methods for modeling protein structures and for determination of structures are still improving their precision, and artifacts of the method exist. So their accuracy is realized if they are reproduced by other methods. It is on such foundations that reproducible data mining is based. Data rates are expanding considerably be they at synchrotrons, the X-ray free electron lasers (XFELs), electron cryomicroscopes (cryoEM), or at the neutron facilities. The work of a person as a referee or user with a narrative and its underpinning data may well be complemented in future by artificial intelligence with machine learning, the former for specific refereeing and the latter for the more general validation, both ideally before publication. Examples are described involving rhenium theranostics, the anti-cancer platins and the SARS-CoV-2 main protease.
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Affiliation(s)
- John R Helliwell
- Department of Chemistry, University of Manchester, Manchester, UK.
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The kinetic substitution reactions and structural analysis of manganese(I) acetylacetonato complexes. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Unusual Structural Features in the Adduct of Dirhodium Tetraacetate with Lysozyme. Int J Mol Sci 2021; 22:ijms22031496. [PMID: 33540880 PMCID: PMC7867343 DOI: 10.3390/ijms22031496] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/19/2021] [Accepted: 01/29/2021] [Indexed: 12/11/2022] Open
Abstract
The structures of the adducts formed upon reaction of the cytotoxic paddlewheel dirhodium complex [Rh2(μ-O2CCH3)4] with the model protein hen egg white lysozyme (HEWL) under different experimental conditions are reported. Results indicate that [Rh2(μ-O2CCH3)4] extensively reacts with HEWL:it in part breaks down, at variance with what happens in reactions with other proteins. A Rh center coordinates the side chains of Arg14 and His15. Dimeric Rh–Rh units with Rh–Rh distances between 2.3 and 2.5 Å are bound to the side chains of Asp18, Asp101, Asn93, and Lys96, while a dirhodium unit with a Rh–Rh distance of 3.2–3.4 Å binds the C-terminal carboxylate and the side chain of Lys13 at the interface between two symmetry-related molecules. An additional monometallic fragment binds the side chain of Lys33. These data, which are supported by replicated structural determinations, shed light on the reactivity of dirhodium tetracarboxylates with proteins, providing useful information for the design of new Rh-containing biomaterials with an array of potential applications in the field of catalysis or of medicinal chemistry and valuable insight into the mechanism of action of these potential anticancer agents.
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Abstract
Recent advances in structural studies unveiling the basis of the metal compounds/protein recognition process are discussed.
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Affiliation(s)
- Antonello Merlino
- Department of Chemical Sciences
- University of Naples Federico II
- Complesso Universitario di Monte Sant’Angelo
- Napoli
- Italy
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Kama DV, Frei A, Schutte-Smith M, Brink A, Swart C, Braband H, Alberto R, Roodt A. Exploring preliminary structural relationships and mitochondrial targeting of fac-[MI(CO)3]-bis(diarylphosphino)alkylamine complexes (M = 99Tc, Re). NEW J CHEM 2021. [DOI: 10.1039/d1nj04273d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Preliminary structural relationships in fac-[MI(CO)3]-bis(diarylphosphino)alkylamine complexes (M = 99Tc, Re), antimicrobial and mitochondrial targeting are reported.
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Affiliation(s)
- Dumisani V. Kama
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Angelo Frei
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Marietjie Schutte-Smith
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Alice Brink
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Chantel Swart
- Department of Biochemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Henrik Braband
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Roger Alberto
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Andreas Roodt
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
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Brink A, Helliwell JR. Why is interoperability between the two fields of chemical crystallography and protein crystallography so difficult? IUCRJ 2019; 6:788-793. [PMID: 31576212 PMCID: PMC6760442 DOI: 10.1107/s2052252519010972] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/06/2019] [Indexed: 05/06/2023]
Abstract
The interoperability of chemical and biological crystallographic data is a key challenge to research and its application to pharmaceutical design. Research attempting to combine data from the two disciplines, small-molecule or chemical crystallography (CX) and macromolecular crystallography (MX), will face unique challenges including variations in terminology, software development, file format and databases which differ significantly from CX to MX. This perspective overview spans the two disciplines and originated from the investigation of protein binding to model radiopharmaceuticals. The opportunities of interlinked research while utilizing the two databases of the CSD (Cambridge Structural Database) and the PDB (Protein Data Bank) will be highlighted. The advantages of software that can handle multiple file formats and the circuitous route to convert organometallic small-molecule structural data for use in protein refinement software will be discussed. In addition some pointers to avoid being shipwrecked will be shared, such as the care which must be taken when interpreting data precision involving small molecules versus proteins.
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Affiliation(s)
- Alice Brink
- Department of Chemistry, University of the Free State, Nelson Mandela Drive, Bloemfontein, Free State 9301, South Africa
- Department of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
| | - John R. Helliwell
- Department of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
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Ferraro G, Giorgio A, Mansour AM, Merlino A. Protein-mediated disproportionation of Au(i): insights from the structures of adducts of Au(iii) compounds bearingN,N-pyridylbenzimidazole derivatives with lysozyme. Dalton Trans 2019; 48:14027-14035. [DOI: 10.1039/c9dt02729g] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Structural data of protein/gold adducts suggest protein-mediated reduction of Au(iii) into Au(i) and disproportionation of Au(i) into Au(iii) and Au(0).
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Affiliation(s)
- Giarita Ferraro
- Department of Chemistry “Ugo Schiff”
- University of Florence
- Sesto Fiorentino
- Italy
| | - Anna Giorgio
- Department of Chemical Sciences
- University of Naples Federico II
- Complesso Universitario di Monte Sant'Angelo
- Naples
- Italy
| | | | - Antonello Merlino
- Department of Chemical Sciences
- University of Naples Federico II
- Complesso Universitario di Monte Sant'Angelo
- Naples
- Italy
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