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Costa LMO, Reis IS, Fernandes C, Marques MM, Resende JALC, Krenske EH, Schenk G, Gahan LR, Horn A. Synthesis, characterization and computational investigation of the phosphatase activity of a dinuclear Zinc(II) complex containing a new heptadentate asymmetric ligand. J Inorg Biochem 2023; 239:112064. [PMID: 36410306 DOI: 10.1016/j.jinorgbio.2022.112064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/24/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022]
Abstract
We report the synthesis of a new asymmetric heptadentate ligand based on the 1,3-diaminopropan-2-ol backbone. The ligand 3-[[3-(bis-pyridin-2-ylmethyl-amino)-2-hydroxy-propyl]-(2-carbamoyl-ethyl)-amino]-propionamide (HL1) contains two amide and two pyridine groups attached to the 1,3-diaminopropan-2-ol core. Reaction between HL1 and Zn(ClO4)2.6H2O resulted in the formation of the dinuclear [Zn2(L1)(μ-OAc)](ClO4)2 complex, characterized by single crystal X-ray diffraction, 1H, 13C and 15N NMR, ESI-(+)-MS, CHN elemental analysis as well as infrared spectroscopy. The phosphatase activity of the complex was studied in the pH range 6-11 employing pyridinium bis(2,4-dinitrophenyl)phosphate (py(BDNPP)) as substrate. The complex exhibited activity dependent on the pH, presenting an asymmetric bell shape profile with the highest activity at pH 9; at high pH ligand exchange is rate-limiting. The hydrolysis of BDNPP- at pH 9 displayed behavior characteristic of Michaelis-Menten kinetics, with kcat = 5.06 × 10-3 min-1 and Km = 5.7 ± 1.0 mM. DFT calculations map out plausible reaction pathways and identify a terminal, Zn(II)-bound hydroxide as likely nucleophile.
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Affiliation(s)
- Luel M O Costa
- Laboratório de Ciências Químicas, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, RJ 28013-602, Brazil
| | - Iago S Reis
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
| | - Christiane Fernandes
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
| | - Marcelo M Marques
- Colégio Universitário Geraldo Reis, Universidade Federal Fluminense, Niterói, RJ 24210-200, Brazil
| | - Jackson A L C Resende
- Instituto de Ciências Exatas e da Terra, Universidade Federal de Mato Grosso, Pontal do Araguaia, MT, Brazil
| | - Elizabeth H Krenske
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia; Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland, Australia, 4072; Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Adolfo Horn
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil.
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Wilson LA, Pedroso MM, Peralta RA, Gahan LR, Schenk G. Biomimetics for purple acid phosphatases: A historical perspective. J Inorg Biochem 2023; 238:112061. [PMID: 36371912 DOI: 10.1016/j.jinorgbio.2022.112061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 10/23/2022] [Accepted: 10/29/2022] [Indexed: 11/06/2022]
Abstract
Biomimetics hold potential for varied applications in biotechnology and medicine but have also attracted particular interest as benchmarks for the functional study of their more complex biological counterparts, e.g. metalloenzymes. While many of the synthetic systems adequately mimic some structural and functional aspects of their biological counterparts the catalytic efficiencies displayed are mostly far inferior due to the smaller size and the associated lower complexity. Nonetheless they play an important role in bioinorganic chemistry. Numerous examples of biologically inspired and informed artificial catalysts have been reported, designed to mimic a plethora of chemical transformations, and relevant examples are highlighted in reviews and scientific reports. Herein, we discuss biomimetics of the metallohydrolase purple acid phosphatase (PAP), examples of which have been used to showcase synergistic research advances for both the biological and synthetic systems. In particular, we focus on the seminal contribution of our colleague Prof. Ademir Neves, and his group, pioneers in the design and optimization of suitable ligands that mimic the active site of PAP.
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Affiliation(s)
- Liam A Wilson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Marcelo M Pedroso
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Rosely A Peralta
- Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
| | - Lawrence R Gahan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland 4072, Australia; Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland 4072, Australia; Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Queensland 4072, Australia.
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3
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Nambigari N, Kodipaka A, Vuradi RK, Airva PK, Sirasani S. A Biophysical Study of Ru(II) Polypyridyl Complex, Properties and its Interaction with DNA. J Fluoresc 2022; 32:1211-1228. [PMID: 35353277 DOI: 10.1007/s10895-021-02879-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/17/2021] [Indexed: 10/18/2022]
Abstract
Mononuclear Ru(II)Polypyridyl complexes of type [Ru(A)2BPIIP] (ClO4)2.2H2O, where BPIIP = 2-(3-(4-bromophenyl)isoxazole-5-yl)-1 H-imidazo [4,5-f] [1, 10] phenanthroline and A = bpy = bipyridyl (1), phen = 1,10 Phenanthroline (2), dmb = 4, 4' -dimethyl 2, 2'- bipyridine (3) & dmp = 4,4'-dimethyl-1,10 -Ortho Phenanthroline (4), were synthesized and their antibacterial activity were examined. The synthesized complexes were characterized and their interaction with DNA was studied using Computational and Biophysical methods (Absorption, emission methods, and viscosity). Molecular modelling studies were carried out for molecular geometry and electronic properties (Frontier molecular orbital HOMO-LUMO). The electrostatic potential surface contours for the complexes were analysed to give their nucleophilic level of sensitivity. The study reveals that the Ru(II) Polypyridyl complexes bind to DNA preponderantly by intercalation. The results recommend that the phen and dmp complex have more effective binding ability than the bpy and dmb, indicating the role of the ancillary ligand in determining their specificity for DNA binding. Further molecular docking studies suggested an octahedral geometry and bind to DNA by preferential binding to Guanine. The docking study additionally sustains the binding constant data acquired with the absorption and emission techniques.The results reveal that the nature of the ancillary Ligand plays a considerable role for the intercalation of the Ru(II) polypyridyl complex to DNA, which subsequently influences the antibacterial activity. Biological studies conducted on Gram-Negative (E.coli and K.pneumonia) and Gram-Positive (S. aureus and E. faecalis) bacteria establish that complex 1 and 2 were considerably active against S. aureus and E. coli.
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Affiliation(s)
- Navaneetha Nambigari
- Department of Chemistry, University College of Science, Osmania University, Saifabad, Telangana State, 500004, India. .,Department of Chemistry, University College of Science, Osmania University, Tarnaka, Telangana State, 500007, India.
| | - Aruna Kodipaka
- Department of Chemistry, University College of Science, Osmania University, Saifabad, Telangana State, 500004, India
| | - Ravi Kumar Vuradi
- Department of Chemistry, University College of Science, Osmania University, Tarnaka, Telangana State, 500007, India
| | - Praveen Kumar Airva
- Department of Biotechnology, Sri Satya Sai University of Technology & Medical Sciences, Bhopal- Indore Road, Opp. Oilfed Plant, Sehore, Madhya Pradesh, 466001, India
| | - Satyanarayana Sirasani
- Department of Chemistry, University College of Science, Osmania University, Tarnaka, Telangana State, 500007, India.
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Foley W, Arman H, Musie GT. Homodinuclear copper(II) and zinc(II) complexes of a carboxylate-rich ligand as synthetic mimics of phosphoester hydrolase in aqueous solutions. J Inorg Biochem 2021; 225:111589. [PMID: 34530333 DOI: 10.1016/j.jinorgbio.2021.111589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 07/14/2021] [Accepted: 08/18/2021] [Indexed: 11/28/2022]
Abstract
The synthesis, characterization and catalytic activities of two homodinuclear Cu(II) and Zn(II) complexes of a carboxylate-rich ligand, N,N'-Bis[2-carboxybenzomethyl]-N,N' -Bis[carboxymethyl]-1,3-diaminopropan-2-ol (H5ccdp) ligand towards the hydrolysis of (p-nitrophenyl phosphate) (PNPP) and bis(p-nitrophenyl) phosphate (BNPP) substrates in aqueous systems are described. Kinetic investigations were carried out using UV-Vis spectrophotometric techniques at 25 °C and 37 °C and different pH (7-10) conditions. The kinetic studies revealed that the turnover rate (kcat) values among the PNPP hydrolysis systems, the highest and the lowest kcat values were displayed by [Cu2(ccdp)(μ-OAc)]2- at 2.34 × 10-6 s-1 (pH 8 and 37 °C) and 2.13 × 10-8 s-1 (pH 8 and 25 °C), respectively. However, similar comparisons among the BNPP hydrolysis revealed that highest and the lowest kcat values were displayed by [Zn2(ccdp)(μ-OAc)]2- at 4.64 × 10-8 s-1 (pH 9 and 37 °C) and 2.38 × 10-9 (pH 9 and 25 °C). Significantly enough, the catalyst-substrate adduct species containing a metal bound PNPP and BNPP have been detected by ESI-MS techniques. Additionally, a PNPP-bound copper complex has been isolated and crystalized using single crystal X-ray diffraction technique. Based on the structural and activity information obtained in this study, reaction mechanisms for the hydrolysis of PNPP have been proposed.
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Affiliation(s)
- William Foley
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Hadi Arman
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States
| | - Ghezai T Musie
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249, United States.
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Maurya RR, Mohan V, Singh P, Singh S, Bahadur I. A novel benzimidazole based cadmium (II) dinuclear complex as bioactive material with different coordination number and their interactions with BSA and HSA: Synthesis, characterization and docking studies. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Polynuclear zinc(II) complexes of thiosemicarbazone: Synthesis, X-ray structure and biological evaluation. J Inorg Biochem 2019; 203:110908. [PMID: 31683125 DOI: 10.1016/j.jinorgbio.2019.110908] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 10/21/2019] [Accepted: 10/27/2019] [Indexed: 01/23/2023]
Abstract
Two new dimeric Zn(II) ([{ZnL1(DMSO2)}2]·DMSO (1), [{ZnL2Cl}2] (2)) and a novel tetrameric Zn(II) complex ([(Zn2L3)2(μ-OAc)2(μ3-O)2] (3)), where H2L1 = 4-(p-methoxyphenyl) thiosemicarbazone of o-hydroxynapthaldehyde, HL2 = 4-(p-methoxyphenyl)thiosemicarbazone of benzoyl pyridine and H2L3 = 4-(p-chlorophenyl)thiosemicarbazone of o-vanillin are reported. Ligands and their complexes were characterized by spectroscopic and single crystal X-ray diffraction techniques. In addition, the complexes exhibited good binding affinity towards HSA (1012 M-1), which is supported by their ability to quench the tryptophan fluorescence emission spectra of HSA. The complexes were also screened for their DNA binding propensity through UV-vis absorption titration, circular dichroism and fluorescence spectral studies. Results show that they effectively interact with CT-DNA through an intercalative mode of binding, with binding constants ranging from 103 to 104 M-1. Among the three complexes 1 has the highest binding affinity towards CT-DNA. Further, the phosphatase activity was evaluated using bis(2,4-dinitrophenyl)phosphate (BDNPP) as substrate, however, the complexes did not yield any measurable catalytic activity. Nevertheless the complexes showed significant cytotoxic potential against HeLa and HT-29 cancer cell lines that was assessed through MTT assay and DAPI staining. Remarkably, complex 1 showed better activity than cisplatin against HT-29 cell line.
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7
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Guanidine- and purine-functionalized ligands of FeIIIZnII complexes: effects on the hydrolysis of DNA. J Biol Inorg Chem 2019; 24:675-691. [DOI: 10.1007/s00775-019-01680-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 06/21/2019] [Indexed: 01/01/2023]
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8
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Wang Q, Li HX, Wang KM, Wang X, Xue Z, Jia L, Du L, Zhao QH. Markov Chain Monte Carlo (MCMC) Method for Studying Magnetic Behaviors in Trinuclear Cobalt(II) Compound. Chem Asian J 2018; 13:1415-1418. [DOI: 10.1002/asia.201800074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 02/24/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Quan Wang
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
| | - Hang-Xing Li
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
| | - Kun-Miao Wang
- Key Laboratory of Tobacco Chemistry of Yunnan Province.; R&D Center of China Tobacco Yunnan Industrial Co., Ltd.; Kunming 650000 China
| | - Xiao Wang
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
| | - Zhe Xue
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
| | - Lei Jia
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
| | - Lin Du
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
- Functional Molecules Analysis and Biotransformation key laboratory of Universities; Yunnan University; Kunming 650091 China
| | - Qi-Hua Zhao
- Key Laboratory of Medicinal Chemistry for Natural Resource Education Ministry, School of Chemical Science and Technology Pharmacy; Yunnan University; Kunming 650091 China
- Functional Molecules Analysis and Biotransformation key laboratory of Universities; Yunnan University; Kunming 650091 China
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9
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Selleck C, Clayton D, Gahan LR, Mitić N, McGeary RP, Pedroso MM, Guddat LW, Schenk G. Visualization of the Reaction Trajectory and Transition State in a Hydrolytic Reaction Catalyzed by a Metalloenzyme. Chemistry 2017; 23:4778-4781. [DOI: 10.1002/chem.201700866] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Christopher Selleck
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Daniel Clayton
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Lawrence R. Gahan
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Nataša Mitić
- Department of Chemistry Maynooth University, Maynooth, Co. Kildare Ireland
| | - Ross P. McGeary
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Marcelo Monteiro Pedroso
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Luke W. Guddat
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences The University of Queensland, St. Lucia Queensland 4072 Australia
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Silva GADS, Amorim AL, Souza BD, Gabriel P, Terenzi H, Nordlander E, Neves A, Peralta RA. Synthesis and characterization of FeIII(μ-OH)ZnII complexes: effects of a second coordination sphere and increase in the chelate ring size on the hydrolysis of a phosphate diester and DNA. Dalton Trans 2017; 46:11380-11394. [DOI: 10.1039/c7dt02035j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Effects of a second coordination sphere and of the chelate ring size in FeIII(μ-OH)ZnII complexes properties and catalysis.
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Affiliation(s)
| | - André Luiz Amorim
- Departamento de Química
- Universidade Federal de Santa Catarina
- 88040-900 Florianópolis
- Brazil
| | - Bernardo de Souza
- Departamento de Química
- Universidade Federal de Santa Catarina
- 88040-900 Florianópolis
- Brazil
| | - Philipe Gabriel
- Centro de Biologia Molecular Estrutural
- Departamento de Bioquímica
- Universidade Federal de Santa Catarina
- Florianópolis
- Brazil
| | - Hernán Terenzi
- Centro de Biologia Molecular Estrutural
- Departamento de Bioquímica
- Universidade Federal de Santa Catarina
- Florianópolis
- Brazil
| | - Ebbe Nordlander
- Inorganic Chemistry Research Group
- Chemical Physics
- Center for Chemistry and Chemical Engineering
- Lund University
- SE-221 00 Lund
| | - Ademir Neves
- Departamento de Química
- Universidade Federal de Santa Catarina
- 88040-900 Florianópolis
- Brazil
| | - Rosely A. Peralta
- Departamento de Química
- Universidade Federal de Santa Catarina
- 88040-900 Florianópolis
- Brazil
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11
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Zerón P, Westphal M, Comba P, Flores-Álamo M, Stueckl AC, Leal-Cervantes C, Ugalde-Saldívar VM, Gasque L. Dinuclear Copper(II) Complexes with Distant Metal Centers: Weaker Donor Groups Increase Catecholase Activity. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201600967] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Paulino Zerón
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México; CDMX 04510 Ciudad Universitaria México
| | - Michael Westphal
- Anorganisch-Chemisches Institut und Interdisciplinäres Zentrum für Wissenschaftliches Rechnen (IWR); Universität Heidelberg; INF 270 69120 Heidelberg Germany
| | - Peter Comba
- Anorganisch-Chemisches Institut und Interdisciplinäres Zentrum für Wissenschaftliches Rechnen (IWR); Universität Heidelberg; INF 270 69120 Heidelberg Germany
| | - Marcos Flores-Álamo
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México; CDMX 04510 Ciudad Universitaria México
| | - A. Claudia Stueckl
- Institut für Anorganische Chemie; Georg-August-Universtität; Tammannstrasse 4 37073 Göttingen Germany
| | - Carmen Leal-Cervantes
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México; CDMX 04510 Ciudad Universitaria México
| | - Víctor M. Ugalde-Saldívar
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México; CDMX 04510 Ciudad Universitaria México
| | - Laura Gasque
- Departamento de Química Inorgánica y Nuclear; Facultad de Química; Universidad Nacional Autónoma de México; CDMX 04510 Ciudad Universitaria México
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Bosch S, Comba P, Gahan LR, Schenk G. Asymmetric mono- and dinuclear Ga III and Zn II complexes as models for purple acid phosphatases. J Inorg Biochem 2016; 162:343-355. [DOI: 10.1016/j.jinorgbio.2015.12.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 12/18/2015] [Accepted: 12/28/2015] [Indexed: 10/22/2022]
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13
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Kutin Y, Srinivas V, Fritz M, Kositzki R, Shafaat HS, Birrell J, Bill E, Haumann M, Lubitz W, Högbom M, Griese JJ, Cox N. Divergent assembly mechanisms of the manganese/iron cofactors in R2lox and R2c proteins. J Inorg Biochem 2016; 162:164-177. [PMID: 27138102 DOI: 10.1016/j.jinorgbio.2016.04.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 04/04/2016] [Accepted: 04/12/2016] [Indexed: 01/22/2023]
Abstract
A manganese/iron cofactor which performs multi-electron oxidative chemistry is found in two classes of ferritin-like proteins, the small subunit (R2) of class Ic ribonucleotide reductase (R2c) and the R2-like ligand-binding oxidase (R2lox). It is unclear how a heterodimeric Mn/Fe metallocofactor is assembled in these two related proteins as opposed to a homodimeric Fe/Fe cofactor, especially considering the structural similarity and proximity of the two metal-binding sites in both protein scaffolds and the similar first coordination sphere ligand preferences of MnII and FeII. Using EPR and Mössbauer spectroscopies as well as X-ray anomalous dispersion, we examined metal loading and cofactor activation of both proteins in vitro (in solution). We find divergent cofactor assembly mechanisms for the two systems. In both cases, excess MnII promotes heterobimetallic cofactor assembly. In the absence of FeII, R2c cooperatively binds MnII at both metal sites, whereas R2lox does not readily bind MnII at either site. Heterometallic cofactor assembly is favored at substoichiometric FeII concentrations in R2lox. FeII and MnII likely bind to the protein in a stepwise fashion, with FeII binding to site 2 initiating cofactor assembly. In R2c, however, heterometallic assembly is presumably achieved by the displacement of MnII by FeII at site 2. The divergent metal loading mechanisms are correlated with the putative in vivo functions of R2c and R2lox, and most likely with the intracellular MnII/FeII concentrations in the host organisms from which they were isolated.
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Affiliation(s)
- Yuri Kutin
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Vivek Srinivas
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Matthieu Fritz
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Ramona Kositzki
- Institut für Experimentalphysik, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Hannah S Shafaat
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - James Birrell
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Eckhard Bill
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Michael Haumann
- Institut für Experimentalphysik, Freie Universität Berlin, D-14195 Berlin, Germany
| | - Wolfgang Lubitz
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden; Department of Chemistry, Stanford University, Stanford, CA 94305, United States.
| | - Julia J Griese
- Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
| | - Nicholas Cox
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany; Research School of Chemistry, Australian National University, Canberra, ACT 2601, Australia.
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