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Bhatti T, Kumar A, Parihar A, Moncy HK, Emge TJ, Waldie KM, Hasanayn F, Goldman AS. Metal-Ligand Proton Tautomerism, Electron Transfer, and C(sp 3)-H Activation by a 4-Pyridinyl-Pincer Iridium Hydride Complex. J Am Chem Soc 2023; 145:18296-18306. [PMID: 37552857 PMCID: PMC10450815 DOI: 10.1021/jacs.3c03376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Indexed: 08/10/2023]
Abstract
The para-N-pyridyl-based PCP pincer proligand 3,5-bis(di-tert-butylphosphinomethyl)-2,6-dimethylpyridine (pN-tBuPCP-H) was synthesized and metalated to give the iridium complex (pN-tBuPCP)IrHCl (2-H). In marked contrast with its phenyl-based congeners, e.g., (tBuPCP)IrHCl and derivatives, 2-H is highly air-sensitive and reacts with oxidants such as ferrocenium, trityl cation, and benzoquinone. These oxidations ultimately lead to intramolecular activation of a phosphino-t-butyl C(sp3)-H bond and cyclometalation. Considering the greater electronegativity of N than C, 2-H is expected to be less easily oxidized than simple PCP derivatives; cyclic voltammetry and DFT calculations support this expectation. However, 2-H is calculated to undergo metal-ligand-proton tautomerism (MLPT) to give an N-protonated complex that can be described with resonance forms representing a zwitterionic complex (with a negative charge on Ir) and a p-N-pyridylidene (a remote N-heterocyclic carbene) Ir(I) complex. One-electron oxidation of this tautomer is calculated to be dramatically more favorable than direct oxidation of 2-H (ΔΔG° = -31.3 kcal/mol). The resulting Ir(II) oxidation product is easily deprotonated to give metalloradical 2• which is observed by NMR spectroscopy. 2• can be further oxidized to give cationic Ir(III) complex, 2+, which can oxidatively add a phosphino-t-butyl C-H bond and undergo deprotonation to give the observed cyclometalated product. DFT calculations indicate that less sterically hindered analogues of 2+ would preferentially undergo intermolecular addition of C(sp3)-H bonds, for example, of n-alkanes. The resulting iridium alkyl complexes could undergo facile β-H elimination to afford olefin, thereby completing a catalytic cycle for alkane dehydrogenation driven by one-electron oxidation and deprotonation, enabled by MLPT.
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Affiliation(s)
- Tariq
M. Bhatti
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Akshai Kumar
- Centre
for Nanotechnology, Indian Institute of
Technology Guwahati, Guwahati 781039, Assam, India
| | - Ashish Parihar
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Hellan K. Moncy
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Thomas J. Emge
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Kate M. Waldie
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Faraj Hasanayn
- Department
of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Alan S. Goldman
- Department
of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
- Centre
for Nanotechnology, Indian Institute of
Technology Guwahati, Guwahati 781039, Assam, India
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2
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Palladium Complexes bearing aromatic Bis-aldimine N^N^N Pincer ligands; Activity as Catalysts in the Hydrogenation of Carbon Dioxide. Polyhedron 2023. [DOI: 10.1016/j.poly.2023.116360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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3
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Miya N, Makuve N, Ocansey E, Mehlana G, Darkwa J, Makhubela BC. Palladium Complexes bearing Bis-aldimine N^C^N and N^N^N Pincer Ligands; A study of Homogeneous/Heterogeneous catalyzed CO2 hydrogenation. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.121207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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4
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Swisher NA, Grubbs RH. Synthesis and Characterization of 3,5-Bis(di- tert-butylphosphinito)pyridine Pincer Complexes. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicholas A. Swisher
- Arnold and Mabel Beckman Laboratory for Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, United States
| | - Robert H. Grubbs
- Arnold and Mabel Beckman Laboratory for Chemical Synthesis, California Institute of Technology, Pasadena, California 91125, United States
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5
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Shi R, Wodrich MD, Pan H, Tirani FF, Hu X. Functional Models of the Nickel Pincer Nucleotide Cofactor of Lactate Racemase. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201910490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Renyi Shi
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI BCH 3305 Lausanne 1015 Switzerland
| | - Matthew D. Wodrich
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI BCH 3305 Lausanne 1015 Switzerland
- Laboratory for Computational Molecular DesignInstitute of Chemical Science and EngineeringEcole Polytechnique Fédérale de Lausanne (EPFL) Lausanne 1015 Switzerland
| | - Hui‐Jie Pan
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI BCH 3305 Lausanne 1015 Switzerland
| | - Farzaneh Fadaei Tirani
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI BCH 3305 Lausanne 1015 Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and CatalysisInstitute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI BCH 3305 Lausanne 1015 Switzerland
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6
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Desage‐El Murr M. Nature is the Cure: Engineering Natural Redox Cofactors for Biomimetic and Bioinspired Catalysis. ChemCatChem 2019. [DOI: 10.1002/cctc.201901642] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Marine Desage‐El Murr
- Institut de Chimie UMR 7177Université de Strasbourg 1 rue Blaise Pascal Strasbourg 67000 France
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7
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Shi R, Wodrich MD, Pan HJ, Tirani FF, Hu X. Functional Models of the Nickel Pincer Nucleotide Cofactor of Lactate Racemase. Angew Chem Int Ed Engl 2019; 58:16869-16872. [PMID: 31535787 DOI: 10.1002/anie.201910490] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Indexed: 11/06/2022]
Abstract
A novel nickel pincer cofactor was recently discovered in lactate racemase. Reported here are three synthetic nickel pincer complexes that are both structural and functional models of the pincer cofactor in lactate racemase. DFT computations suggest the ipso-carbon atom of the pyridinium pincer ligands act as a hydride acceptor for lactate isomerization, whereas an organometallic pathway involving nickel-mediated β-hydride elimination is less favored.
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Affiliation(s)
- Renyi Shi
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne, 1015, Switzerland
| | - Matthew D Wodrich
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne, 1015, Switzerland.,Laboratory for Computational Molecular Design, Institute of Chemical Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015, Switzerland
| | - Hui-Jie Pan
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne, 1015, Switzerland
| | - Farzaneh Fadaei Tirani
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne, 1015, Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), ISIC-LSCI, BCH 3305, Lausanne, 1015, Switzerland
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Abstract
The advancements of quantum chemical methods and computer power allow detailed mechanistic investigations of metalloenzymes. In particular, both quantum chemical cluster and combined QM/MM approaches have been used, which have been proven to successfully complement experimental studies. This review starts with a brief introduction of nickel-dependent enzymes and then summarizes theoretical studies on the reaction mechanisms of these enzymes, including NiFe hydrogenase, methyl-coenzyme M reductase, nickel CO dehydrogenase, acetyl CoA synthase, acireductone dioxygenase, quercetin 2,4-dioxygenase, urease, lactate racemase, and superoxide dismutase.
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10
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Mohammadnezhad G, Abad S, Farrokhpour H. Theoretical studies on the thermodynamics and kinetics of one-pot synthesis of aromatic PCP and PNP pincer ligands. Struct Chem 2017. [DOI: 10.1007/s11224-017-1002-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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11
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Desguin B, Soumillion P, Hausinger RP, Hols P. Unexpected complexity in the lactate racemization system of lactic acid bacteria. FEMS Microbiol Rev 2017; 41:S71-S83. [DOI: 10.1093/femsre/fux021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/11/2017] [Indexed: 12/30/2022] Open
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12
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Yu MJ, Chen SL. From NAD + to Nickel Pincer Complex: A Significant Cofactor Evolution Presented by Lactate Racemase. Chemistry 2017; 23:7545-7557. [PMID: 28374531 DOI: 10.1002/chem.201700405] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Indexed: 02/02/2023]
Abstract
Lactate racemase (LarA), a new nickel enzyme discovered recently, catalyzes the racemization between d- and l-lactates with a novel nickel pincer cofactor (Ni-PTTMN) derived from nicotinic acid. In this study, by using DFT and a 200-atom active-site model, LarA is revealed to employ a modified proton-coupled hydride-transfer mechanism in which a hydride is transferred to a cofactor pyridine carbon from the substrate α-carbon along with proton transfer from the substrate hydroxy group to a histidine, and then moved back from the opposite side. Tyr294 and Lys298 provide significant acceleration effects by orientating substrates and stabilizing the negative charge developing at the substrate hydroxy oxygen. The barrier was determined to be 12.0 kcal mol-1 , which reveals enhanced racemase activity relative to the LarA reaction using NAD+ -like cofactors. Compared with NAD+ , Ni-PTTMN has a stronger hydride-addition reactivity in moderate and high environmental polarity and may fit perfectly the moderately polar active site of LarA.
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Affiliation(s)
- Ming-Jia Yu
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P.R. China
| | - Shi-Lu Chen
- Key Laboratory of Cluster Science of the Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, P.R. China
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13
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Xu T, Wodrich MD, Scopelliti R, Corminboeuf C, Hu X. Nickel pincer model of the active site of lactate racemase involves ligand participation in hydride transfer. Proc Natl Acad Sci U S A 2017; 114:1242-1245. [PMID: 28115700 PMCID: PMC5307482 DOI: 10.1073/pnas.1616038114] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lactate racemase is the first enzyme known to possess a metal pincer active site. The enzyme interconverts d- and l-lactic acid, which is important for the assembly of cell walls in many microorganisms. Here, we report a synthetic model of the active site of lactate racemase, which features a pyridinium-based SCS pincer ligand framework bound to nickel. The model complex mediates the dehydrogenation of alcohols, a reaction relevant to lactate racemization. Experimental and computational data indicate ligand participation in the dehydrogenation reaction.
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Affiliation(s)
- Tao Xu
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Matthew D Wodrich
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Rosario Scopelliti
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland
| | - Xile Hu
- Laboratory of Inorganic Synthesis and Catalysis, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland;
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14
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Wang B, Shaik S. The Nickel-Pincer Complex in Lactate Racemase Is an Electron Relay and Sink that acts through Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2017; 56:10098-10102. [DOI: 10.1002/anie.201612065] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Indexed: 11/05/2022]
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
| | - 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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15
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Wang B, Shaik S. The Nickel-Pincer Complex in Lactate Racemase Is an Electron Relay and Sink that acts through Proton-Coupled Electron Transfer. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201612065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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
| | - 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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16
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Qiu B, Yang X. A bio-inspired design and computational prediction of scorpion-like SCS nickel pincer complexes for lactate racemization. Chem Commun (Camb) 2017; 53:11410-11413. [DOI: 10.1039/c7cc06416k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computationally predicted scorpion-like SCS nickel pincer complexes are promising for the catalysis of lactate racemization under mild conditions.
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Affiliation(s)
- Bing Qiu
- Beijing National Laboratory for Molecular Sciences
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species
- CAS Research/Education Center for Excellence in Molecular Sciences
- Institute of Chemistry
- Chinese Academy of Sciences
| | - Xinzheng Yang
- Beijing National Laboratory for Molecular Sciences
- State Key Laboratory for Structural Chemistry of Unstable and Stable Species
- CAS Research/Education Center for Excellence in Molecular Sciences
- Institute of Chemistry
- Chinese Academy of Sciences
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17
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Zhang X, Chung LW. Alternative Mechanistic Strategy for Enzyme Catalysis in a Ni-Dependent Lactate Racemase (LarA): Intermediate Destabilization by the Cofactor. Chemistry 2016; 23:3623-3630. [DOI: 10.1002/chem.201604893] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Xiaoyong Zhang
- Department of Chemistry; South University of Science and Technology of China; Shenzhen 518055 P. R. China
| | - Lung W. Chung
- Department of Chemistry; South University of Science and Technology of China; Shenzhen 518055 P. R. China
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Nickel-pincer cofactor biosynthesis involves LarB-catalyzed pyridinium carboxylation and LarE-dependent sacrificial sulfur insertion. Proc Natl Acad Sci U S A 2016; 113:5598-603. [PMID: 27114550 DOI: 10.1073/pnas.1600486113] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The lactate racemase enzyme (LarA) of Lactobacillus plantarum harbors a (SCS)Ni(II) pincer complex derived from nicotinic acid. Synthesis of the enzyme-bound cofactor requires LarB, LarC, and LarE, which are widely distributed in microorganisms. The functions of the accessory proteins are unknown, but the LarB C terminus resembles aminoimidazole ribonucleotide carboxylase/mutase, LarC binds Ni and could act in Ni delivery or storage, and LarE is a putative ATP-using enzyme of the pyrophosphatase-loop superfamily. Here, we show that LarB carboxylates the pyridinium ring of nicotinic acid adenine dinucleotide (NaAD) and cleaves the phosphoanhydride bond to release AMP. The resulting biscarboxylic acid intermediate is transformed into a bisthiocarboxylic acid species by two single-turnover reactions in which sacrificial desulfurization of LarE converts its conserved Cys176 into dehydroalanine. Our results identify a previously unidentified metabolic pathway from NaAD using unprecedented carboxylase and sulfur transferase reactions to form the organic component of the (SCS)Ni(II) pincer cofactor of LarA. In species where larA is absent, this pathway could be used to generate a pincer complex in other enzymes.
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