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Wang B, Zhang X, Fang W, Rovira C, Shaik S. How Do Metalloproteins Tame the Fenton Reaction and Utilize •OH Radicals in Constructive Manners? Acc Chem Res 2022; 55:2280-2290. [PMID: 35926175 DOI: 10.1021/acs.accounts.2c00304] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
This Account describes the manner whereby nature controls the Fenton-type reaction of O-O homolysis of hydrogen peroxide and harnesses it to carry out various useful oxidative transformations in metalloenzymes. H2O2 acts as the cosubstrate for the heme-dependent peroxidases, P450BM3, P450SPα, P450BSβ, and the P450 decarboxylase OleT, as well as the nonheme enzymes HppE and the copper-dependent lytic polysaccharide monooxygenases (LPMOs). Whereas heme peroxidases use the Poulos-Kraut heterolytic mechanism for H2O2 activation, some heme enzymes prefer the alternative Fenton-type mechanism, which produces •OH radical intermediates. The fate of the •OH radical is controlled by the protein environment, using tight H-bonding networks around H2O2. The so-generated •OH radical is constrained by the surrounding H-bonding interactions, the orientation of which is targeted to perform H-abstraction from the Fe(III)-OH group and thereby leading to the formation of the active species, called Compound I (Cpd I), Por+•Fe(IV)═O, which performs oxidation of the substrate. Alternatively, for the nonheme HppE enzyme, the O-O homolysis catalyzed by the resting state Fe(II) generates an Fe(III)-OH species that effectively constrains the •OH radical species by a tight H-bonding network. The so-formed H-bonded •OH radical acts directly as the oxidant, since it is oriented to perform H-abstraction from the C-H bond of the substrate (S)-2-HPP. The Fenton-type H2O2 activation is strongly suggested by computations to occur also in copper-dependent LPMOs and pMMO. In LPMOs, the Cu(I)-catalyzed O-O homolysis of the H2O2 cosubstrate generates an •OH radical that abstracts a hydrogen atom from Cu(II)-OH and forms thereby the active species of the enzyme, Cu(II)-O•. Such Fenton-type O-O activation can be shared by both the O2-dependent activations of LPMOs and pMMOs, in which the O2 cosubstrate may be reduced to H2O2 by external reductants. Our studies show that, generally, the H2O2 activation is highly dependent on the protein environment, as well as on the presence/absence of substrates. Since H2O2 is a highly flexible and hydrophilic molecule, the absence of suitable substrates may lead to unproductive binding or even to the release of H2O2 from the active site, as has been suggested in P450cam and LPMOs, whereas the presence of the substrate seems to play a role in steering a Fenton-type H2O2 activation. In the absence of a substrate, the hydrophilic active site of P450BM3 disfavors the binding and activation of H2O2 and protects thereby the enzyme from the damage by the Fenton reaction. Due to the distinct coordination and reaction environment, the Fenton-type H2O2 activation mechanism by enzymes differs from the reaction in synthetic systems. In nonenzymatic reactions, the H-bonding networks are quite dynamic and flexible and the reactivity of H2O2 is not strategically constrained as in the enzymatic environment. As such, our Account describes the controlled Fenton-type mechanism in metalloenzymes, and the role of the protein environment in constraining the •OH radical against oxidative damage, while directing it to perform useful oxidative transformations.
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Affiliation(s)
- Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Xuan Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Wenhan Fang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China
| | - Carme Rovira
- Departament de Química Inorgànica i Orgànica & IQTCUB, Universitat de Barcelona, 08028 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), 08020 Barcelona, Spain
| | - Sason Shaik
- Institute of Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel
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Zhang S, Li X, Wang Y, Yan L, Wei J, Liu Y. Computational Study of the C5-Hydroxylation Mechanism Catalyzed by the Diiron Monooxygenase PtmU3 as Part of the Platensimycin Biosynthesis. Inorg Chem 2021; 60:17783-17796. [PMID: 34762413 DOI: 10.1021/acs.inorgchem.1c02407] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PtmU3 is a newly identified nonheme diiron monooxygenase, which installs a C-5 β-hydroxyl group into the C-19 CoA-ester intermediate involved in the biosynthesis of unique diterpene-derived scaffolds of platensimycin and platencin. PtmU3 possesses a noncanonical diiron active site architecture of a saturated six-coordinate iron center and lacks the μ-oxo bridge. Although the hydroxylation process is a simple reaction for nonheme mononuclear iron-dependent enzymes, how PtmU3 employs the diiron center to catalyze the H-abstraction and OH-rebound is still unknown. In particular, the electronic characteristic of diiron is also unclear. To understand the catalytic mechanism of PtmU3, we constructed two reactant models in which both the Fe1II-Fe2III-superoxo and Fe1II-Fe2IV═O are considered to trigger the H-abstraction and performed a series of quantum mechanics/molecular mechanics calculations. Our calculation results reveal that PtmU3 is a special monooxygenase, that is, both atoms of the dioxygen molecule can be incorporated into two molecules of the substrate by the successive reactions. In the first-round reaction, PtmU3 uses the Fe1II-Fe2III-superoxo to install a hydroxyl group into the substrate, generating the high-reactive Fe1II-Fe2IV═O complex. In the second-round reaction, the Fe1II-Fe2IV═O species is responsible for the hydroxylation of another molecule of the substrate. In the diiron center, Fe2 adopts the high spin state (S = 5/2) during the catalysis, whereas for Fe1, in addition to its structural role, it may also play an assistant role for Fe1 catalysis. In the two successive OH-installing steps, the H-abstraction is always the rate-liming step. E241 and D308 not only act as bridging ligands to connect two Fe ions but also take part in the electron reorganization. Owing to the high reactivity of Fe1II-Fe2IV═O compared to Fe1II-Fe2III-superoxo, besides the C5-hydroxylation, the C3- or C18-hydroxylation was also calculated to be feasible.
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Affiliation(s)
- Shiqing Zhang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
| | - Xinyi Li
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
| | - Yijing Wang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
| | - Lijuan Yan
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
| | - Jingjing Wei
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, Shandong, China
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Lu J, Wang B, Shaik S, Lai W. QM/MM Calculations Reveal the Important Role of α-Heteroatom Substituents in Controlling Selectivity of Mononuclear Nonheme HppE-Catalyzed Reactions. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01803] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Jiarui Lu
- Department of Chemistry, Renmin University of China, Beijing 100872, China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 360015, P. R. China
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Wenzhen Lai
- Department of Chemistry, Renmin University of China, Beijing 100872, China
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4
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Lu J, Lai W. Mechanistic Insights into a Stibene Cleavage Oxygenase NOV1 from Quantum Mechanical/Molecular Mechanical Calculations. ChemistryOpen 2019; 8:228-235. [PMID: 30828510 PMCID: PMC6382310 DOI: 10.1002/open.201800259] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/30/2019] [Indexed: 12/03/2022] Open
Abstract
NOV1, a stilbene cleavage oxygenase, catalyzes the cleavage of the central double bond of stilbenes to two phenolic aldehydes, using a 4-His Fe(II) center and dioxygen. Herein, we use in-protein quantum mechanical/molecular mechanical (QM/MM) calculations to elucidate the reaction mechanism of the central double bond cleavage of phytoalexin resveratrol by NOV1. Our results showed that the oxygen molecule prefers to bind to the iron center in a side-on fashion, as suggested from the experiment. The quintet Fe-O2 complex with the side-on superoxo antiferromagnetic coupled to the resveratrol radical is identified as the reactive oxygen species. The QM/MM results support the dioxygenase mechanism involving a dioxetane intermediate with a rate-limiting barrier of 10.0 kcal mol-1. The alternative pathway through an epoxide intermediate is ruled out due to a larger rate-limiting barrier (26.8 kcal mol-1). These findings provide important insight into the catalytic mechanism of carotenoid cleavage oxygenases and also the dioxygen activation of non-heme enzymes.
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Affiliation(s)
- Jiarui Lu
- Department of ChemistryRenmin University of ChinaNo. 59 Zhongguancun Street, Haidian DistrictBeijing100872P. R. China
| | - Wenzhen Lai
- Department of ChemistryRenmin University of ChinaNo. 59 Zhongguancun Street, Haidian DistrictBeijing100872P. R. China
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Wang WJ, Wei WJ, Liao RZ. Deciphering the chemoselectivity of nickel-dependent quercetin 2,4-dioxygenase. Phys Chem Chem Phys 2018; 20:15784-15794. [DOI: 10.1039/c8cp02683a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
QM/MM calculations were performed to elucidate the reaction mechanism and chemoselectivity of 2,4-QueD. The protonation state of the first-shell ligand Glu74 plays an important role in dictating the selectivity.
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Affiliation(s)
- Wen-Juan Wang
- Key Laboratory of Material Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
| | - Wen-Jie Wei
- Key Laboratory of Material Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
| | - Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage
- Ministry of Education
- Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica
- Hubei Key Laboratory of Materials Chemistry and Service Failure
- School of Chemistry and Chemical Engineering
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6
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Sato S, Kudo F, Kim SY, Kuzuyama T, Eguchi T. Methylcobalamin-Dependent Radical SAM C-Methyltransferase Fom3 Recognizes Cytidylyl-2-hydroxyethylphosphonate and Catalyzes the Nonstereoselective C-Methylation in Fosfomycin Biosynthesis. Biochemistry 2017; 56:3519-3522. [PMID: 28678474 DOI: 10.1021/acs.biochem.7b00472] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A methylcobalamin (MeCbl)-dependent radical S-adenosyl-l-methionine (SAM) methyltransferase Fom3 was found to catalyze the C-methylation of cytidylyl-2-hydroxyethylphosphonate (HEP-CMP) to give cytidylyl-2-hydroxypropylphosphonate (HPP-CMP), although it was originally proposed to catalyze the C-methylation of 2-hydroxyethylphosphonate to give 2-hydroxypropylphosphonate in the biosynthesis of a unique C-P bond containing antibiotic fosfomycin in Streptomyces. Unexpectedly, the Fom3 reaction product from HEP-CMP was almost a 1:1 diastereomeric mixture of HPP-CMP, indicating that the C-methylation is not stereoselective. Presumably, only the CMP moiety of HEP-CMP is critical for substrate recognition; on the other hand, the enzyme does not fix the 2-hydroxy group of the substrate and either of the prochiral hydrogen atoms at the C2 position can be abstracted by the 5'-deoxyadenosyl radical generated from SAM to form the substrate radical intermediates, which react with MeCbl to afford the corresponding products. This strict substrate recognition mechanism with no stereoselectivity of a MeCbl-dependent radical SAM methyltransferase is remarkable in natural product biosynthetic chemistry, because such a hidden clue for selective substrate recognition is likely to be found in the other biosynthetic pathways.
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Affiliation(s)
- Shusuke Sato
- Department of Chemistry, Tokyo Institute of Technology , 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Fumitaka Kudo
- Department of Chemistry, Tokyo Institute of Technology , 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
| | - Seung-Young Kim
- Biotechnology Research Center, The University of Tokyo , 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tomohisa Kuzuyama
- Biotechnology Research Center, The University of Tokyo , 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tadashi Eguchi
- Department of Chemistry, Tokyo Institute of Technology , 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8551, Japan
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Wei WJ, Siegbahn PEM, Liao RZ. Theoretical Study of the Mechanism of the Nonheme Iron Enzyme EgtB. Inorg Chem 2017; 56:3589-3599. [PMID: 28277674 DOI: 10.1021/acs.inorgchem.6b03177] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
EgtB is a nonheme iron enzyme catalyzing the C-S bond formation between γ-glutamyl cysteine (γGC) and N-α-trimethyl histidine (TMH) in the ergothioneine biosynthesis. Density functional calculations were performed to elucidate and delineate the reaction mechanism of this enzyme. Two different mechanisms were considered, depending on whether the sulfoxidation or the S-C bond formation takes place first. The calculations suggest that the S-O bond formation occurs first between the thiolate and the ferric superoxide, followed by homolytic O-O bond cleavage, very similar to the case of cysteine dioxygenase. Subsequently, proton transfer from a second-shell residue Tyr377 to the newly generated iron-oxo moiety takes place, which is followed by proton transfer from the TMH imidazole to Tyr377, facilitated by two crystallographically observed water molecules. Next, the S-C bond is formed between γGC and TMH, followed by proton transfer from the imidazole CH moiety to Tyr377, which was calculated to be the rate-limiting step for the whole reaction, with a barrier of 17.9 kcal/mol in the quintet state. The calculated barrier for the rate-limiting step agrees quite well with experimental kinetic data. Finally, this proton is transferred back to the imidazole nitrogen to form the product. The alternative thiyl radical attack mechanism has a very high barrier, being 25.8 kcal/mol, ruling out this possibility.
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Affiliation(s)
- Wen-Jie Wei
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology , Wuhan 430074, China
| | - Per E M Siegbahn
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , SE-10691 Stockholm, Sweden
| | - Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology , Wuhan 430074, China
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8
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Dong G, Ryde U. O2 Activation in Salicylate 1,2-Dioxygenase: A QM/MM Study Reveals the Role of His162. Inorg Chem 2016; 55:11727-11735. [DOI: 10.1021/acs.inorgchem.6b01732] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Geng Dong
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, SE-221 00 Lund, Sweden
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P.O. Box 124, SE-221 00 Lund, Sweden
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9
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Wang B, Lu J, Dubey KD, Dong G, Lai W, Shaik S. How do Enzymes Utilize Reactive OH Radicals? Lessons from Nonheme HppE and Fenton Systems. J Am Chem Soc 2016; 138:8489-96. [PMID: 27309496 DOI: 10.1021/jacs.6b03555] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The iron(IV)-oxo (ferryl) intermediate has been amply established as the principal oxidant in nonheme enzymes and the key player in C-H bond activations and functionalizations. In contrast to this status, our present QM/MM calculations of the mechanism of fosfomycin biosynthesis (a broad range antibiotic) by the nonheme HppE enzyme rule out the iron(IV)-oxo as the reactive species in the hydrogen abstraction (H-abstraction) step of the pro-R hydrogen from the (S)-2-hydroxypropylphosphonic substrate. Moreover, the study reveals that the ferryl species is bypassed in HppE, while the actual oxidant is an HO(•) radical hydrogen-bonded to a ferric-hydroxo complex, resulting via the homolytic dissociation of the hydrogen peroxide complex, Fe(II)-H2O2. The computed energy barrier of this pathway is 12.0 kcal/mol, in fair agreement with the experimental datum of 9.8 kcal/mol. An alternative mechanism involves the iron-complexed hydroxyl radical (Fe(III)-(HO(•))) that is obtained by protonation of the iron(IV)-oxo group via the O-H group of the substrate. The barrier for this pathway, 23.0 kcal/mol, is higher than the one in the first mechanism. In both mechanisms, the HO(•) radical is highly selective; its H-abstraction leading to the final cis-fosfomycin product. It appears that HppE is prone to usage of HO(•) radicals for C-H bond activation, because the ferryl oxidant requires a specific H-abstraction trajectory (∠FeOH ∼ 180°) that cannot be met for intramolecular H-abstraction. Thus, this work broadens the landscape of nonheme iron enzymes and makes a connection to Fenton chemistry, with implications on new potential biocatalysts that may harness hydroxyl radicals for C-H bond functionalizations.
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Affiliation(s)
- Binju Wang
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , 91904 Jerusalem, Israel
| | - Jiarui Lu
- Department of Chemistry, Renmin University of China , Beijing 100872, China
| | - Kshatresh Dutta Dubey
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , 91904 Jerusalem, Israel
| | - Geng Dong
- Department of Chemistry, Renmin University of China , Beijing 100872, China
| | - Wenzhen Lai
- Department of Chemistry, Renmin University of China , Beijing 100872, China
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , 91904 Jerusalem, Israel
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10
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Mono- and binuclear non-heme iron chemistry from a theoretical perspective. J Biol Inorg Chem 2016; 21:619-44. [DOI: 10.1007/s00775-016-1357-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/29/2016] [Indexed: 10/21/2022]
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11
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Qi SC, Hayashi JI, Zhang L. Recent application of calculations of metal complexes based on density functional theory. RSC Adv 2016. [DOI: 10.1039/c6ra16168e] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Recent application of density functional theory (DFT) for metal complexes is reviewed to show the achievements of DFT and the challenges for it, as well as the methods for selecting proper functionals.
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Affiliation(s)
- Shi-Chao Qi
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Kasuga
- Japan
| | - Jun-ichiro Hayashi
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Kasuga
- Japan
| | - Lu Zhang
- Institute for Materials Chemistry and Engineering
- Kyushu University
- Kasuga
- Japan
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12
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Feng JS, Ren M, Cai ZS, Fan K, Bao SS, Zheng LM. Enantiopure phosphonic acids as chiral inducers: homochiral crystallization of cobalt coordination polymers showing field-induced slow magnetization relaxation. Chem Commun (Camb) 2016; 52:6877-80. [DOI: 10.1039/c6cc02463g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Homochiral crystallization of (M)- or (P)-Co(SO4)(1,3-bbix)(H2O)3 (1M or 1P) from an achiral precursor is achieved in the presence of a catalytic amount of (S)- or (R)-3-phenyl-2-((phosphonomethyl)amino) propanoic acid.
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Affiliation(s)
- Jian-Shen Feng
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
| | - Min Ren
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
| | - Zhong-Sheng Cai
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
| | - Kun Fan
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
| | - Song-Song Bao
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
| | - Li-Min Zheng
- State Key Laboratory of Coordination Chemistry
- School of Chemistry and Chemical Engineering
- Collaborative Innovation Center of Advanced Microstructures
- Nanjing University
- Nanjing 210093
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13
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Boaz NC, Bell SR, Groves JT. Ferryl protonation in oxoiron(IV) porphyrins and its role in oxygen transfer. J Am Chem Soc 2015; 137:2875-85. [PMID: 25651467 PMCID: PMC4363944 DOI: 10.1021/ja508759t] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Ferryl porphyrins, P-Fe(IV)═O, are central reactive intermediates in the catalytic cycles of numerous heme proteins and a variety of model systems. There has been considerable interest in elucidating factors, such as terminal oxo basicity, that may control ferryl reactivity. Here, the sulfonated, water-soluble ferryl porphyrin complexes tetramesitylporphyrin, oxoFe(IV)TMPS (FeTMPS-II), its 2,6-dichlorophenyl analogue, oxoFe(IV)TDClPS (FeTDClPS-II), and two other analogues are shown to be protonated under turnover conditions to produce the corresponding bis-aqua-iron(III) porphyrin cation radicals. The results reveal a novel internal electromeric equilibrium, P-Fe(IV)═O ⇆ P(+)-Fe(III)(OH2)2. Reversible pKa values in the range of 4-6.3 have been measured for this process by pH-jump, UV-vis spectroscopy. Ferryl protonation has important ramifications for C-H bond cleavage reactions mediated by oxoiron(IV) porphyrin cation radicals in protic media. Both solvent O-H and substrate C-H deuterium kinetic isotope effects are observed for these reactions, indicating that hydrocarbon oxidation by these oxoiron(IV) porphyrin cation radicals occurs via a solvent proton-coupled hydrogen atom transfer from the substrate that has not been previously described. The effective FeO-H bond dissociation energies for FeTMPS-II and FeTDClPS-II were estimated from similar kinetic reactivities of the corresponding oxoFe(IV)TMPS(+) and oxoFe(IV)TDClPS(+) species to be ∼92-94 kcal/mol. Similar values were calculated from the two-proton P(+)-Fe(III)(OH2)2 pKa(obs) and the porphyrin oxidation potentials, despite a 230 mV range for the iron porphyrins examined. Thus, the iron porphyrin with the lower ring oxidation potential has a compensating higher basicity of the ferryl oxygen. The solvent-derived proton adds significantly to the driving force for C-H bond scission.
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Affiliation(s)
- Nicholas C. Boaz
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Seth R. Bell
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - John T. Groves
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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14
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Sheng X, Liu Y, Zhang R. A theoretical study of the catalytic mechanism of oxalyl-CoA decarboxylase, an enzyme for treating urolithiasis. RSC Adv 2014. [DOI: 10.1039/c4ra03611e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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15
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Blomberg MRA, Borowski T, Himo F, Liao RZ, Siegbahn PEM. Quantum chemical studies of mechanisms for metalloenzymes. Chem Rev 2014; 114:3601-58. [PMID: 24410477 DOI: 10.1021/cr400388t] [Citation(s) in RCA: 431] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Margareta R A Blomberg
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University , SE-106 91 Stockholm, Sweden
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16
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Geronimo I, Paneth P. A DFT and ONIOM study of C–H hydroxylation catalyzed by nitrobenzene 1,2-dioxygenase. Phys Chem Chem Phys 2014; 16:13889-99. [DOI: 10.1039/c4cp01030b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The DFT and ONIOM calculations show that C–H hydroxylation by nitrobenzene 1,2-dioxygenase proceeds through a HO–FeVO intermediate.
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Affiliation(s)
- Inacrist Geronimo
- Institute of Applied Radiation Chemistry
- Lodz University of Technology
- 90-924 Łódź, Poland
| | - Piotr Paneth
- Institute of Applied Radiation Chemistry
- Lodz University of Technology
- 90-924 Łódź, Poland
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Borowski T, Broclawik E. Bioinorganic Reaction Mechanisms – Quantum Chemistry Approach. ACTA ACUST UNITED AC 2014. [DOI: 10.1007/978-3-642-28554-7_22] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Raushel FM. Not an Oxidase, But a Peroxidase. Science 2013; 342:943-4. [DOI: 10.1126/science.1247233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A key step in the biosynthesis of the antibiotic fosfomycin requires hydrogen peroxide, rather than molecular oxygen as previously assumed.
[Also see Report by
Wang
et al.
]
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Affiliation(s)
- Frank M. Raushel
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
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Wang C, Chang WC, Guo Y, Huang H, Peck SC, Pandelia ME, Lin GM, Liu HW, Krebs C, Bollinger JM. Evidence that the fosfomycin-producing epoxidase, HppE, is a non-heme-iron peroxidase. Science 2013; 342:991-5. [PMID: 24114783 PMCID: PMC4160821 DOI: 10.1126/science.1240373] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The iron-dependent epoxidase HppE converts (S)-2-hydroxypropyl-1-phosphonate (S-HPP) to the antibiotic fosfomycin [(1R,2S)-epoxypropylphosphonate] in an unusual 1,3-dehydrogenation of a secondary alcohol to an epoxide. HppE has been classified as an oxidase, with proposed mechanisms differing primarily in the identity of the O2-derived iron complex that abstracts hydrogen (H•) from C1 of S-HPP to initiate epoxide ring closure. We show here that the preferred cosubstrate is actually H2O2 and that HppE therefore almost certainly uses an iron(IV)-oxo complex as the H• abstractor. Reaction with H2O2 is accelerated by bound substrate and produces fosfomycin catalytically with a stoichiometry of unity. The ability of catalase to suppress the HppE activity previously attributed to its direct utilization of O2 implies that reduction of O2 and utilization of the resultant H2O2 were actually operant.
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Affiliation(s)
- Chen Wang
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, USA
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Sheng X, Liu Y. Theoretical study of the catalytic mechanism of E1 subunit of pyruvate dehydrogenase multienzyme complex from Bacillus stearothermophilus. Biochemistry 2013; 52:8079-93. [PMID: 24171427 DOI: 10.1021/bi400577f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyruvate dehydrogenase multienzyme complex (PDHc) is a member of a family of 2-oxo acid dehydrogenase (OADH) multienzyme complexes involved in several central points of oxidative metabolism, and the E1 subunit is the most important component in the entire PDHc catalytic system, which catalyzes the reversible transfer of an acetyl group from a pyruvate to the lipoyl group of E2 subunit lipoly domain. In this article, the catalytic mechanism of the E1 subunit has been systematically studied using density functional theory (DFT). Four possible pathways with different general acid/base catalysts in decarboxylation and reductive acylation processes were explored. Our calculation results indicate that the 4'-amino pyrimidine of ThDP and residue His128 are the most likely proton donors in the decarboxylation and reductive acylation processes, respectively. During the reaction, each C-C and C-S bond formation or cleavage process, except for the liberation of CO2, is always accompanied by a proton transfer between the substrates and proton donors. The liberation of CO2 is calculated to be the rate-limiting step for the overall reaction, with an energy barrier of 13.57 kcal/mol. The decarboxylation process is endothermic by 5.32 kcal/mol, whereas the reductive acylation process is exothermic with a value of 5.74 kcal/mol. The assignment of protonation states of the surrounding residues can greatly influence the reaction. Residues His128 and His271 play roles in positioning the first substrate pyruvate and second substrate lipoyl group, respectively.
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Affiliation(s)
- Xiang Sheng
- Key Laboratory of Theoretical and Computational Chemistry in Universities of Shandong, School of Chemistry and Chemical Engineering, Shandong University , Jinan, Shandong 250100, China
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Dong G, Shaik S, Lai W. Oxygen activation by homoprotocatechuate 2,3-dioxygenase: a QM/MM study reveals the key intermediates in the activation cycle. Chem Sci 2013. [DOI: 10.1039/c3sc51147b] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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