1
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Gonzalez M, Guberman-Pfeffer MJ, Koone JC, Dashnaw CM, Lato TJ, Shaw BF. Proton-coupled electron transfer at a mis-metalated zinc site detected with protein charge ladders. Phys Chem Chem Phys 2024; 26:22870-22881. [PMID: 39193659 PMCID: PMC11350471 DOI: 10.1039/d4cp01989j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Accepted: 08/12/2024] [Indexed: 08/29/2024]
Abstract
Distinguishing proton-coupled electron transfer (PCET) from uncoupled electron transfer (ET) in proteins can be challenging. A recent investigation [J. C. Koone, M. Simmang, D. L. Saenger, M. L. Hunsicker-Wang and B. F. Shaw, J. Am. Chem. Soc., 145, 16488-16497] reported that protein charge ladders and capillary electrophoresis can distinguish between single ET, PCET, and two-proton coupled ET (2PCET) by directly measuring the change in protein net charge upon reduction/oxidation (ΔZET). The current study used similar methods to assess PCET in zinc-free, "double copper" superoxide dismutase-1 (4Cu-SOD1), where one copper is bound at the copper site of each monomer and one copper is bound at the bridging zinc site, resulting in a quasi-type III Cu center. At pH 7.4, the net charge (Z) of the 4Cu-SOD1 dimer was unaffected by reduction of all four Cu2+ ions, i.e., ΔZ4ET = -0.09 ± 0.05 per dimer (-0.02 ± 0.01 per copper atom). These values suggest that PCET is taking place at all four Cu atoms of the homodimer. Molecular dynamics and Poisson-Boltzmann calculations suggest that a metal-coordinating histidine at the zinc site (His71) is the proton acceptor. These data show how ligands of a naturally occurring zinc site can help facilitate PCET when the right redox metal is bound.
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Affiliation(s)
- Mayte Gonzalez
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
| | | | - Jordan C Koone
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
| | - Chad M Dashnaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
| | - Travis J Lato
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
| | - Bryan F Shaw
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, USA.
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2
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Hota PK, Panda S, Phan H, Kim B, Siegler MA, Karlin KD. Dioxygenase Chemistry in Nucleophilic Aldehyde Deformylations Utilizing Dicopper O 2-Derived Peroxide Complexes. J Am Chem Soc 2024; 146:23854-23871. [PMID: 39141923 DOI: 10.1021/jacs.4c06243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
The chemistry of copper-dioxygen complexes is relevant to copper enzymes in biology as well as in (ligand)Cu-O2 (or Cu2-O2) species utilized in oxidative transformations. For overall energy considerations, as applicable in chemical synthesis, it is beneficial to have an appropriate atom economy; both O-atoms of O2(g) are transferred to the product(s). However, examples of such dioxygenase-type chemistry are extremely rare or not well documented. Herein, we report on nucleophilic oxidative aldehyde deformylation reactivity by the peroxo-dicopper(II) species [Cu2II(BPMPO-)(O22-)]1+ {BPMPO-H = 2,6-bis{[(bis(2-pyridylmethyl)amino]methyl}-4-methylphenol)} and [Cu2II(XYLO-)(O22-)]1+ (XYLO- = a BPMPO- analogue possessing bis(2-{2-pyridyl}ethyl)amine chelating arms). Their dicopper(I) precursors are dioxygenase catalysts. The O2(g)-derived peroxo-dicopper(II) intermediates react rapidly with aldehydes like 2-phenylpropionaldehyde (2-PPA) and cyclohexanecarboxaldehyde (CCA) in 2-methyltetrahydrofuran at -90 °C. Warming to room temperature (RT) followed by workup results in good yields of formate (HC(O)O-) along with ketones (acetophenone or cyclohexanone). Mechanistic investigation shows that [Cu2II(BPMPO-)(O22-)]1+ species initially reacts reversibly with the aldehydes to form detectable dicopper(II) peroxyhemiacetal intermediates, for which optical titrations provide the Keq (at -90 °C) of 73.6 × 102 M-1 (2-PPA) and 10.4 × 102 M-1 (CCA). In the reaction of [Cu2II(XYLO-)(O22-)]1+ with 2-PPA, product complexes characterized by single-crystal X-ray crystallography are the anticipated dicopper(I) complex, [Cu2I(XYLO-)]1+ plus a mixed-valent Cu(I)Cu(II)-formate species. Formate was further identified and confirmed by 1H NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) analysis. Using 18O2(g)-isotope labeling the reaction produced a high yield of 18-O incorporated acetophenone as well as formate. The overall results signify that true dioxygenase reactions have occurred, supported by a thorough mechanistic investigation.
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Affiliation(s)
- Pradip Kumar Hota
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Sanjib Panda
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hai Phan
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Bohee Kim
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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3
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Di Costanzo LF. Structural characterization of tyrosinases and an update on human enzymes. Enzymes 2024; 56:55-83. [PMID: 39304291 DOI: 10.1016/bs.enz.2024.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2024]
Abstract
Tyrosinase, a pivotal enzyme in melanin biosynthesis, orchestrates the pigmentation process in humans, affecting skin, hair, and eye color. This chapter examines the three-dimensional structure and functional aspects of tyrosinases from various sources, highlighting their di-metal ion coordination crucial for catalytic activity. I explore the biochemical pathwayscheme catalyzed by tyrosinase, specifically the oxidation of L-tyrosine to L-dopaquinone, a precursor in melanin synthesis. Detailed structural analyses, including 3D structures obtained from X-ray crystallography and computational modeling, reveal key insights into the enzyme's active site, variations among tyrosinases, and substrate binding mechanisms. Furthermore, the chapter investigates the role of human tyrosinase variants, their inhibitors, essential for developing therapeutic and cosmetic applications targeting hyperpigmentation disorders. Structural characterizations of tyrosinase-inhibitor complexes provide a foundation for designing effective inhibitors, with compounds like kojic acid, L-mimosine, and (S)-3-amino-tyrosine demonstrating significant inhibitory potential. This comprehensive examination of the structure, function, and inhibition mechanisms of tyrosinase offers avenues for innovative treatments in biotechnology, health, and beyond.
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Affiliation(s)
- Luigi Franklin Di Costanzo
- Department of Agriculture, Department of Excellence, University of Naples Federico II, Palace of Portici, Piazza Carlo di Borbone, Portici NA, Italy.
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4
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Motovilov KA, Mostert AB. Melanin: Nature's 4th bioorganic polymer. SOFT MATTER 2024; 20:5635-5651. [PMID: 39012013 DOI: 10.1039/d4sm00491d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
The pigments known as the melanins are widely recognized for their responsibility in the coloration of human skin, eyes, hair, and minimising the harmful effects of solar ultraviolet radiation. But specialists are aware that the melanins are present in all living kingdoms, barring viruses, and have functionality that extends beyond neutralizing ionising radiation. The ubiquitous presence of melanin in almost all human organs, recognized in recent years, as well as the presence of melanin in organisms that are evolutionarily distant from each other, indicate the fundamental importance of this class of material for all life forms. In this review, we argue for the need to accept melanins as the fourth primordial class of biological polymers, along with nucleic acids, proteins and polysaccharides. We consistently compare the properties of these canonical biological polymers with the properties of melanin and highlight key features that fundamentally distinguish melanins, their function and its mysteries.
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Affiliation(s)
- K A Motovilov
- Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny 141701, Moscow Region, Russia.
| | - A B Mostert
- Department of Physics and Centre for Integrative Semiconductor Materials, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EN, UK
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5
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De Tovar J, Leblay R, Wang Y, Wojcik L, Thibon-Pourret A, Réglier M, Simaan AJ, Le Poul N, Belle C. Copper-oxygen adducts: new trends in characterization and properties towards C-H activation. Chem Sci 2024; 15:10308-10349. [PMID: 38994420 PMCID: PMC11234856 DOI: 10.1039/d4sc01762e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Accepted: 05/11/2024] [Indexed: 07/13/2024] Open
Abstract
This review summarizes the latest discoveries in the field of C-H activation by copper monoxygenases and more particularly by their bioinspired systems. This work first describes the recent background on copper-containing enzymes along with additional interpretations about the nature of the active copper-oxygen intermediates. It then focuses on relevant examples of bioinorganic synthetic copper-oxygen intermediates according to their nuclearity (mono to polynuclear). This includes a detailed description of the spectroscopic features of these adducts as well as their reactivity towards the oxidation of recalcitrant Csp3 -H bonds. The last part is devoted to the significant expansion of heterogeneous catalytic systems based on copper-oxygen cores (i.e. within zeolite frameworks).
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Affiliation(s)
- Jonathan De Tovar
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
| | - Rébecca Leblay
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Yongxing Wang
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Laurianne Wojcik
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | | | - Marius Réglier
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - A Jalila Simaan
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Institut des Sciences Moléculaires de Marseille Marseille France
| | - Nicolas Le Poul
- Université de Brest, Laboratoire de Chimie, Electrochimie Moléculaires et Chimie Analytique Brest France
| | - Catherine Belle
- Université Grenoble-Alpes, CNRS, Département de Chimie Moléculaire Grenoble France
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6
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Panda S, Phan H, Dunietz EM, Brueggemeyer MT, Hota PK, Siegler MA, Jose A, Bhadra M, Solomon EI, Karlin KD. Intramolecular Phenolic H-Atom Abstraction by a N 3ArOH Ligand-Supported (μ-η 2:η 2-Peroxo)dicopper(II) Species Relevant to the Active Site Function of oxy-Tyrosinase. J Am Chem Soc 2024; 146:14942-14947. [PMID: 38775712 PMCID: PMC11193493 DOI: 10.1021/jacs.4c04402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Synthetic side-on peroxide-bound dicopper(II) (SP) complexes are important for understanding the active site structure/function of many copper-containing enzymes. This work highlights the formation of new {CuII(μ-η2:η2-O22-)CuII} complexes (with electronic absorption and resonance Raman (rR) spectroscopic characterization) using tripodal N3ArOH ligands at -135 °C, which spontaneously participate in intramolecular phenolic H-atom abstraction (HAA). This results in the generation of bis(phenoxyl radical)bis(μ-OH)dicopper(II) intermediates, substantiated by their EPR/UV-vis/rR spectroscopic signatures and crystal structural determination of a diphenoquinone dicopper(I) complex derived from ligand para-C═C coupling. The newly observed chemistry in these ligand-Cu systems is discussed with respect to (a) our Cu-MeAN (tridentate N,N,N',N',N″-pentamethyldipropylenetriamine)-derived model SP species, which was unreactive toward exogenous monophenol addition (J. Am. Chem. Soc. 2012, 134, 8513-8524), emphasizing the impact of intramolecularly tethered ArOH groups, and (b) recent advances in understanding the mechanism of action of the tyrosinase (Ty) enzyme.
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Affiliation(s)
- Sanjib Panda
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Hai Phan
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Eleanor M Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | | | - Pradip Kumar Hota
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Anex Jose
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mayukh Bhadra
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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7
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Zolghadri S, Saboury AA. Catalytic mechanism of tyrosinases. Enzymes 2024; 56:31-54. [PMID: 39304290 DOI: 10.1016/bs.enz.2024.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2024]
Abstract
Tyrosinases (TYR) play a key role in melanin biosynthesis by catalyzing two reactions: monophenolase and diphenolase activities. Despite low amino acid sequence homology, TYRs from various organisms (from bacteria to humans) have similar active site architectures and catalytic mechanisms. The active site of the TYRs contains two copper ions coordinated by histidine (His) residues. The catalytic mechanism of TYRs involves electron transfer between copper sites, leading to the hydroxylation of monophenolic compounds to diphenols and the subsequent oxidation of these to corresponding dopaquinones. Although extensive studies have been conducted on the structure, catalytic mechanism, and enzymatic capabilities of TYRs, some mechanistic aspects are still debated. This chapter will delve into the structure of the active site, catalytic function, and inhibition mechanism of TYRs. The goal is to improve our understanding of the molecular mechanisms underlying TYR activity. This knowledge can help in developing new strategies to modulate TYR function and potentially treat diseases linked to melanin dysregulation.
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Affiliation(s)
- Samaneh Zolghadri
- Department of Biology, Jahrom Branch, Islamic Azad University, Jahrom, Iran.
| | - Ali Akbar Saboury
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
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8
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Arora S, Rawal P, Gupta P. Orbital Analysis Captures the Existence of a Mixed-Valent Cu III -O-Cu II Active-Site and its Role in Water-Assisted Aliphatic Hydroxylation. Chemistry 2024; 30:e202303722. [PMID: 38168869 DOI: 10.1002/chem.202303722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 12/31/2023] [Accepted: 01/03/2024] [Indexed: 01/05/2024]
Abstract
The Cu-O-Cu core has been proposed as a potential site for methane oxidation in particulate methane monooxygenase. In this work, we used density functional theory (DFT) to design a mixed-valent CuIII -O-CuII species from an experimentally known peroxo-dicopper complex supported by N-donor ligands containing phenolic groups. We found that the transfer of two-protons and two-electrons from phenolic groups to peroxo-dicopper core takes place, which results to the formation of a bis-μ-hydroxo-dicopper core. The bis-μ-hydroxo-dicopper core converts to a mixed-valent CuIII -O-CuII core with the removal of a water molecule. The orbital and spin density analyses unravel the mixed-valent nature of CuIII -O-CuII . We further investigated the reactivity of this mixed-valent core for aliphatic C-H hydroxylation. Our study unveiled that mixed-valent CuIII -O-CuII core follows a hydrogen atom transfer mechanism for C-H activation. An in-situ generated water molecule plays an important role in C-H hydroxylation by acting as a proton transfer bridge between carbon and oxygen. Furthermore, to assess the relevance of a mixed-valent CuIII -O-CuII core, we investigated aliphatic C-H activation by a symmetrical CuII -O-CuII core. DFT results show that the mixed-valent CuIII -O-CuII core is more reactive toward the C-H bond than the symmetrical CuII -O-CuII core.
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Affiliation(s)
- Sumangla Arora
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667
| | - Parveen Rawal
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667
| | - Puneet Gupta
- Computational Catalysis Center, Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667
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9
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Jiang H, Zhou L, Wang Y, Liu G, Peng S, Yu W, Tian Y, Liu J, Liu W. Inhibition of cinnamic acid and its derivatives on polyphenol oxidase: Effect of inhibitor carboxyl group and system pH. Int J Biol Macromol 2024; 259:129285. [PMID: 38211907 DOI: 10.1016/j.ijbiomac.2024.129285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 01/04/2024] [Accepted: 01/04/2024] [Indexed: 01/13/2024]
Abstract
Phenolic acids are promising inhibitors of polyphenol oxidase (PPO), but the effects of carboxyl group and pH on their inhibition effects are still unclear. In this study, methyl cinnamate, cinnamic acid and 4-carboxycinnamic acid were investigated by their inhibitory effects with pH varied from 6.8 to 5.0. Results showed that 4-carboxycinnamic acid had the strongest inhibitory effect on PPO, followed by cinnamic acid and methyl cinnamate. Acidic pH enhanced the inhibitory effects of cinnamic acid and its derivatives on PPO, and the enhancement degree, IC50 and Ki declining degree were followed as 4-carboxycinnamic acid > cinnamic acid > methyl cinnamate. Methyl cinnamate exhibited competitive inhibition on PPO, while cinnamic acid and 4-carboxycinnamic acid exhibited mixed-type inhibition. Inhibitors induced slight changes in the secondary and tertiary structures of PPO, which were enhanced by acidic pH. Molecular docking results showed that 4-carboxycinnamic acid exhibited the strongest binding ability, and the main interaction forces were around carboxyl groups, and acidic pH enhanced the binding effect through more interactions and lower binding energy. This study could provide new insights into industrial application of cinnamic acid and its derivatives for the control of enzymatic browning of fruits and vegetables.
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Affiliation(s)
- Hongwei Jiang
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Lei Zhou
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China.
| | - Yue Wang
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Guangxian Liu
- Institute of Agricultural Products Processing, Jiangxi Academy of Agricultural Sciences, Nanchang, Jiangxi 330200, China
| | - Shengfeng Peng
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Wenzhi Yu
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Yuqing Tian
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Junping Liu
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China
| | - Wei Liu
- State Key Laboratory of Food Science and Resources, Nanchang University, Nanchang 330047, China; National R&D Center for Freshwater Fish Processing, Jiangxi Normal University, Nanchang 330022, China
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10
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Pham TN, Cazier EA, Gormally E, Lawrence P. Valorization of biomass polyphenols as potential tyrosinase inhibitors. Drug Discov Today 2024; 29:103843. [PMID: 38000718 DOI: 10.1016/j.drudis.2023.103843] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 11/08/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023]
Abstract
Tyrosinases (TYRs; EC 1.14.18.1) catalyze two sequential oxidative reactions of the melanin biosynthesis pathway and play an important role in mammalian pigmentation and enzymatic browning of fruit and vegetables. Inhibition of TYR activity is therefore an attractive target for new drugs and/or food ingredients. In addition, increasing evidence suggests that TYR regulation could be a novel target for treatments of cancer and Parkinson's disease. Biomasses, notably industrial byproducts and biowaste, are good sustainable sources of phytochemicals that may be valorized into bioactive compounds including TYR inhibitors. This review presents potential applications of biomass-derived polyphenols targeting TYR inhibition. Insights into structure-activity relationships of several polyphenols and their glycosides are highlighted. Finally, some remarks and perspectives on research into new TYR inhibitors from biomass waste are provided.
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Affiliation(s)
- Thanh-Nhat Pham
- UCLy (Lyon Catholic University), ESTBB, Lyon, France; UCLy (Lyon Catholic University), UR CONFLUENCE: Sciences et Humanités (EA 1598), Lyon, France.
| | - Elisabeth A Cazier
- UCLy (Lyon Catholic University), ESTBB, Lyon, France; UCLy (Lyon Catholic University), UR CONFLUENCE: Sciences et Humanités (EA 1598), Lyon, France; Nantes Université, Oniris, GEPEA, UMR 6144, F-44600 Saint-Nazaire, France
| | - Emmanuelle Gormally
- UCLy (Lyon Catholic University), ESTBB, Lyon, France; UCLy (Lyon Catholic University), UR CONFLUENCE: Sciences et Humanités (EA 1598), Lyon, France
| | - Philip Lawrence
- UCLy (Lyon Catholic University), ESTBB, Lyon, France; UCLy (Lyon Catholic University), UR CONFLUENCE: Sciences et Humanités (EA 1598), Lyon, France
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11
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Kipouros I, Stańczak A, Dunietz EM, Ginsbach JW, Srnec M, Rulíšek L, Solomon EI. Experimental Evidence and Mechanistic Description of the Phenolic H-Transfer to the Cu 2O 2 Active Site of oxy-Tyrosinase. J Am Chem Soc 2023; 145:22866-22870. [PMID: 37844210 PMCID: PMC10615789 DOI: 10.1021/jacs.3c07450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Tyrosinase is a ubiquitous coupled binuclear copper enzyme that activates O2 toward the regioselective monooxygenation of monophenols to catechols via a mechanism that remains only partially defined. Here, we present new mechanistic insights into the initial steps of this monooxygenation reaction by employing a pre-steady-state, stopped-flow kinetics approach that allows for the direct measurement of the monooxygenation rates for a series of para-substituted monophenols by oxy-tyrosinase. The obtained biphasic Hammett plot and the associated solvent kinetic isotope effect values provide direct evidence for an initial H-transfer from the protonated phenolic substrate to the Cu2O2 core of oxy-tyrosinase. The correlation of these experimental results to quantum mechanics/molecular mechanics calculations provides a detailed mechanistic description of this H-transfer step. These new mechanistic insights revise and expand our fundamental understanding of Cu2O2 active sites in biology.
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Affiliation(s)
- Ioannis Kipouros
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Agnieszka Stańczak
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10, Praha 6, Czech Republic
- Faculty of Science, Charles University, Albertov 2038/6, 128 00 Praha 2, Czech Republic
| | - Eleanor M. Dunietz
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Prague 182 23, Czech Republic
| | - Lubomír Rulíšek
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, Flemingovo náměstí 2, 166 10, Praha 6, Czech Republic
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
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12
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Lo Presti E, Schifano F, Bacchella C, Santagostini L, Casella L, Monzani E. Asymmetric Sulfoxidation by a Tyrosinase Biomimetic Dicopper Complex with a Benzimidazolyl Derivative of L-Phenylalanine. Molecules 2023; 28:molecules28114487. [PMID: 37298963 DOI: 10.3390/molecules28114487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Revised: 05/26/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
A challenge in mimicking tyrosinase activity using model compounds is to reproduce its enantioselectivity. Good enantioselection requires rigidity and a chiral center close to the active site. In this study, the synthesis of a new chiral copper complex, [Cu2(mXPhI)]4+/2+, based on an m-xylyl-bis(imidazole)-bis(benzimidazole) ligand containing a stereocenter with a benzyl residue directly bound on the copper chelating ring, is reported. Binding experiments show that the cooperation between the two metal centers is weak, probably due to steric hindrance given by the benzyl group. The dicopper(II) complex [Cu2(mXPhI)]4+ has catalytic activity in the oxidations of enantiomeric couples of chiral catechols, with an excellent discrimination capability for Dopa-OMe enantiomers and a different substrate dependence, hyperbolic or with substrate inhibition, for the L- or D- enantiomers, respectively. [Cu2(mXPhI)]4+ is active in a tyrosinase-like sulfoxidation of organic sulfides. The monooxygenase reaction requires a reducing co-substrate (NH2OH) and yields sulfoxide with significant enantiomeric excess (e.e.). Experiments with 18O2 and thioanisole yielded sulfoxide with 77% incorporation of 18O, indicating a reaction occurring mostly through direct oxygen transfer from the copper active intermediate to the sulfide. This mechanism and the presence of the chiral center of the ligand in the immediate copper coordination sphere are responsible for the good enantioselectivity observed.
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Affiliation(s)
- Eliana Lo Presti
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Fabio Schifano
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Chiara Bacchella
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Laura Santagostini
- Dipartimento di Chimica, Università di Milano, Via Golgi 19, 20133 Milano, Italy
| | - Luigi Casella
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
| | - Enrico Monzani
- Dipartimento di Chimica, Università di Pavia, Via Taramelli 12, 27100 Pavia, Italy
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Högbom M. Nobel symposium #168 Visions of bio-inorganic chemistry: metals and the molecules of life. FEBS Lett 2023; 597:3-5. [PMID: 36623847 DOI: 10.1002/1873-3468.14559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
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