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Yan W, Poore AT, Yin L, Carter S, Ho YS, Wang C, Yachuw SC, Cheng YH, Krause JA, Cheng MJ, Zhang S, Tian S, Liu W. Catalytically Relevant Organocopper(III) Complexes Formed through Aryl-Radical-Enabled Oxidative Addition. J Am Chem Soc 2024; 146:15176-15185. [PMID: 38770641 DOI: 10.1021/jacs.4c01668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Stepwise oxidative addition of copper(I) complexes to form copper(III) species via single electron transfer (SET) events has been widely proposed in copper catalysis. However, direct observation and detailed investigation of these fundamental steps remain elusive owing largely to the typically slow oxidative addition rate of copper(I) complexes and the instability of the copper(III) species. We report herein a novel aryl-radical-enabled stepwise oxidative addition pathway that allows for the formation of well-defined alkyl-CuIII species from CuI complexes. The process is enabled by the SET from a CuI species to an aryl diazonium salt to form a CuII species and an aryl radical. Subsequent iodine abstraction from an alkyl iodide by the aryl radical affords an alkyl radical, which then reacts with the CuII species to form the alkyl-CuIII complex. The structure of resultant [(bpy)CuIII(CF3)2(alkyl)] complexes has been characterized by NMR spectroscopy and X-ray crystallography. Competition experiments have revealed that the rate at which different alkyl iodides undergo oxidative addition is consistent with the rate of iodine abstraction by carbon-centered radicals. The CuII intermediate formed during the SET process has been identified as a four-coordinate complex, [CuII(CH3CN)2(CF3)2], through electronic paramagnetic resonance (EPR) studies. The catalytic relevance of the high-valent organo-CuIII has been demonstrated by the C-C bond-forming reductive elimination reactivity. Finally, localized orbital bonding analysis of these formal CuIII complexes indicates inverted ligand fields in σ(Cu-CH2) bonds. These results demonstrate the stepwise oxidative addition in copper catalysis and provide a general strategy to investigate the elusive formal CuIII complexes.
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Affiliation(s)
- Wenhao Yan
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Andrew T Poore
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Lingfeng Yin
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Samantha Carter
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Yeu-Shiuan Ho
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Chao Wang
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Stephen C Yachuw
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yu-Ho Cheng
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Jeanette A Krause
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Mu-Jeng Cheng
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan
| | - Shiyu Zhang
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Shiliang Tian
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Wei Liu
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
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2
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Khalifa S, Enomoto M, Nakagawa K. Unveiling an unexpected superoxide-mediated photooxidation mechanism of squalene monohydroperoxides to squalene hydroperoxy cyclic peroxides through ESR and LC-MS/MS analyses. Sci Rep 2023; 13:19525. [PMID: 37945632 PMCID: PMC10636020 DOI: 10.1038/s41598-023-46044-9] [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: 10/06/2023] [Accepted: 10/26/2023] [Indexed: 11/12/2023] Open
Abstract
Lipid cyclic peroxides are a rarely reported and documented class of compounds in the human organism. Recently, we reported the formation of squalene (SQ) hydroperoxy cyclic peroxides derived from SQ monohydroperoxide isomers (SQ-OOHs) for the first time. Notably, we successfully detected and quantified cis-2-OOH-3-(1,2-dioxane)-SQ in the human skin. Nevertheless, the underlying mechanism governing the formation of these compounds remained elusive. Therefore, in the current study, we set to determine the reaction's mechanism. To this end, a comprehensive analysis of the precise conditions involved in the onset and propagation of this conversion was carried out by oxidizing total SQ-OOHs under different conditions, including singlet oxygen (1O2), thermal, and photoinduced oxidations monitored by quantifying the generated 2-OOH-3-(1,2-dioxane)-SQ using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Radical intermediates were thoroughly investigated using Electron Spin Resonance (ESR) with the aid of spin traps and radical references. Moreover, calculations of SQ-OOHs' electrostatic charges were performed on Spartan 18 software. We found that the reaction is ideally induced and favored under photooxidation in the presence of 3O2 in hexane, and that superoxide radical (O2•-) is the first key intermediate in this mechanism, whereas peroxyl radicals were the major species observed throughout the oxidation. Chemical calculations provided an explanation for the targeting of tertiary SQ-OOHs by this reaction and gave further evidence on the proposed heterolytic cleavage initiating the reaction. The novel oxidation mechanism suggested herein offers new insights into understanding lipid secondary oxidation and is a promising finding for further studying lipid cyclic peroxides in general.
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Affiliation(s)
- Saoussane Khalifa
- Laboratory of Food Function Analysis, Graduate School of Agricultural Science, Tohoku University, Sendai, 980-8572, Japan
| | - Masaru Enomoto
- Applied Bioorganic Chemistry Laboratory, Graduate School of Agricultural Science, Tohoku University, Sendai, 980-8572, Japan
| | - Kiyotaka Nakagawa
- Laboratory of Food Function Analysis, Graduate School of Agricultural Science, Tohoku University, Sendai, 980-8572, Japan.
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Salvo J, Sandoval C, Schencke C, Acevedo F, del Sol M. Healing Effect of a Nano-Functionalized Medical-Grade Honey for the Treatment of Infected Wounds. Pharmaceutics 2023; 15:2187. [PMID: 37765158 PMCID: PMC10536296 DOI: 10.3390/pharmaceutics15092187] [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: 07/03/2023] [Revised: 08/06/2023] [Accepted: 08/08/2023] [Indexed: 09/29/2023] Open
Abstract
Based on the qualities of Ulmo honey (Eucryphia cordifolia), a medical-grade honey (Ulmoplus®) has been developed. Relevant to this, the use of copper represents an emerging therapy for the treatment of wounds. Therefore, the aim of this study was to see how this medical-grade honey with copper nanoparticles (CuNPs) helped to heal infected or non-infected wounds. Twenty-four guinea pigs (Cavia porcellus) were divided into four groups for phase 1 (without and with infection, U + F1 and U + F2), and two groups for phase 2 (selected formulation, without and with infection, U + F2NI and U + F2I). Bacteriological and histopathological studies, collagen fibers content evaluation, and stereological analysis were performed. The selected formulation displayed the same antibacterial potency as Ulmoplus®, indicating that this medical-grade honey by itself can be used as an antibacterial agent. However, the evaluation of collagen content demonstrated a significant increase in fibroblast and type III collagen fibers for infected and uninfected groups, which correlated with the histopathological study. Therefore, it is correct to affirm that adding CuNPs to Ulmoplus® improved the maturation of collagen fibers. Finally, polymorphonuclear cells presented similar values between experimental groups, which would indicate that the formulation under study was able to regulate the inflammatory process despite their infectious condition.
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Affiliation(s)
- Jessica Salvo
- Escuela de Enfermería, Facultad de Salud, Universidad Santo Tomás, Temuco 4811230, Chile;
- Programa de Doctorado en Ciencias Morfológicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile
| | - Cristian Sandoval
- Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile;
- Escuela de Tecnología Médica, Facultad de Salud, Universidad Santo Tomás, Los Carreras 753, Osorno 5310431, Chile
| | - Carolina Schencke
- Carrera de Psicología, Facultad de Ciencias Sociales y Humanidades, Universidad Autónoma de Chile, Temuco 4810101, Chile
| | - Francisca Acevedo
- Departamento de Ciencias Básicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile;
- Núcleo Científico-Tecnológico en Biorecursos (BIOREN-UFRO), Universidad de La Frontera, Temuco 4780000, Chile
| | - Mariano del Sol
- Programa de Doctorado en Ciencias Morfológicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile
- Departamento de Ciencias Básicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile;
- Centro de Excelencia en Estudios Morfológicos y Quirúrgicos (CEMyQ), Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile
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4
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Salvo J, Sandoval C, Schencke C, Acevedo F, del Sol M. Healing Effect of a Nano-Functionalized Medical-Grade Honey for the Treatment of Infected Wounds. Pharmaceutics 2023; 15:2187. [DOI: https:/doi.org/10.3390/pharmaceutics15092187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/01/2023] Open
Abstract
Based on the qualities of Ulmo honey (Eucryphia cordifolia), a medical-grade honey (Ulmoplus®) has been developed. Relevant to this, the use of copper represents an emerging therapy for the treatment of wounds. Therefore, the aim of this study was to see how this medical-grade honey with copper nanoparticles (CuNPs) helped to heal infected or non-infected wounds. Twenty-four guinea pigs (Cavia porcellus) were divided into four groups for phase 1 (without and with infection, U + F1 and U + F2), and two groups for phase 2 (selected formulation, without and with infection, U + F2NI and U + F2I). Bacteriological and histopathological studies, collagen fibers content evaluation, and stereological analysis were performed. The selected formulation displayed the same antibacterial potency as Ulmoplus®, indicating that this medical-grade honey by itself can be used as an antibacterial agent. However, the evaluation of collagen content demonstrated a significant increase in fibroblast and type III collagen fibers for infected and uninfected groups, which correlated with the histopathological study. Therefore, it is correct to affirm that adding CuNPs to Ulmoplus® improved the maturation of collagen fibers. Finally, polymorphonuclear cells presented similar values between experimental groups, which would indicate that the formulation under study was able to regulate the inflammatory process despite their infectious condition.
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Affiliation(s)
- Jessica Salvo
- Escuela de Enfermería, Facultad de Salud, Universidad Santo Tomás, Temuco 4811230, Chile
- Programa de Doctorado en Ciencias Morfológicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile
| | - Cristian Sandoval
- Departamento de Ciencias Preclínicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile
- Escuela de Tecnología Médica, Facultad de Salud, Universidad Santo Tomás, Los Carreras 753, Osorno 5310431, Chile
| | - Carolina Schencke
- Carrera de Psicología, Facultad de Ciencias Sociales y Humanidades, Universidad Autónoma de Chile, Temuco 4810101, Chile
| | - Francisca Acevedo
- Departamento de Ciencias Básicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile
- Núcleo Científico-Tecnológico en Biorecursos (BIOREN-UFRO), Universidad de La Frontera, Temuco 4780000, Chile
| | - Mariano del Sol
- Programa de Doctorado en Ciencias Morfológicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4811230, Chile
- Departamento de Ciencias Básicas, Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile
- Centro de Excelencia en Estudios Morfológicos y Quirúrgicos (CEMyQ), Facultad de Medicina, Universidad de La Frontera, Temuco 4780000, Chile
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5
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Tseng IH, Yang YH, Chen YT, Hsu LC. Tailoring Copper Chemical Status and Hydrophobicity of Biomimetic Photocatalytic Films for Carbon Dioxide Conversion. ACS APPLIED MATERIALS & INTERFACES 2023; 15:5038-5048. [PMID: 36629448 DOI: 10.1021/acsami.2c15868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Naturally hierarchical nanostructures of leaves were successfully replicated on thermally stable polyimide (PI) films to obtain biomimetic substrates for the grafting of p-type semiconductor, cuprous oxide (Cu2O). The chemical states of Cu2O and the hydrophobicity on the photocatalytic films were tunable by altering the process time of ion-exchange or chemical reduction. The obtained photocatalytic films showed activity to photocatalytically convert carbon dioxide (CO2) into carbon monoxide (CO) under visible light illumination. The yield of CO was initially improved with the increasing hydrophobicity on the film but then leveled off. The photocatalytic activity could be further improved by tailoring the amount or composition of copper oxides. An optimum ratio of Cu2O and moderate basicity on the surface, as well as more metallic Cu from the bulk, will achieve more efficient interfacial charge transfer, resulting in a higher CO production rate.
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Affiliation(s)
- I-Hsiang Tseng
- Department of Chemical Engineering, Feng Chia University, Taichung407102, Taiwan
| | - Yu-Hsuian Yang
- Department of Chemical Engineering, Feng Chia University, Taichung407102, Taiwan
| | - Yi-Ting Chen
- Department of Chemical Engineering, Feng Chia University, Taichung407102, Taiwan
| | - Liang-Ching Hsu
- National Synchrotron Radiation Research Center, Hsinchu300092, Taiwan
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Wang C, Hansen HCB, Andersen ML, Strobel BW, Ma H, Dodge N, Jensen PE, Lu C, Holm PE. Fast peroxydisulfate oxidation of the antibiotic norfloxacin catalyzed by cyanobacterial biochar. JOURNAL OF HAZARDOUS MATERIALS 2022; 439:129655. [PMID: 35901634 DOI: 10.1016/j.jhazmat.2022.129655] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 06/15/2023]
Abstract
Peroxydisulfate (PDS) is a common oxidant for organic contaminant remediation. PDS is typically activated by metal catalysts to generate reactive radicals. Unfortunately, as radicals are non-selective and metal catalysts may cause secondary contamination, alternative selective non-radical pathways and non-metal catalysts need attention. Here we investigated PDS oxidation of commonly detected antibiotic Norfloxacin (NOR) using cyanobacterial nitrogen rich biochars (CBs) as catalysts. NOR was fully degraded by CB pyrolysed at 950 °C (CB950) within 120 min. CB950 caused threefold faster degradation than low pyrolysis temperature (PT) CBs and achieved a maximum surface area normalized rate constant of 4.38 × 10-2 min-1 m-2 L compared to widely used metal catalysts. CB950 maintained full reactivity after four repeated uses. High defluorination (82%) and mineralization (>82%) were observed for CB950/PDS. CBs were active over a broad pH range (3-10), but with twice as high rates under alkaline compared with neutral conditions. NOR is degraded by organic, •OH and SO4•- radicals in low PT CBs/PDS systems, where the presence of MnII promotes radical generation. Electron transfer reactions with radicals supplemented dominate high PT CBs/PDS systems. This study demonstrates high PT biochars from algal bloom biomass may find use as catalysts for organic contaminant oxidation.
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Affiliation(s)
- Chen Wang
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark.
| | - Hans Christian Bruun Hansen
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Mogens Larsen Andersen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Bjarne W Strobel
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Hui Ma
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Nadia Dodge
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Poul Erik Jensen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Changyong Lu
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
| | - Peter E Holm
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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Chen L, Duan J, Du P, Sun W, Lai B, Liu W. Accurate identification of radicals by in-situ electron paramagnetic resonance in ultraviolet-based homogenous advanced oxidation processes. WATER RESEARCH 2022; 221:118747. [PMID: 35728498 DOI: 10.1016/j.watres.2022.118747] [Citation(s) in RCA: 115] [Impact Index Per Article: 57.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/28/2022] [Accepted: 06/12/2022] [Indexed: 06/15/2023]
Abstract
Accurate identification of radicals in advanced oxidation processes (AOPs) is important to study the mechanisms on radical production and subsequent oxidation-reduction reaction. The commonly applied radical quenching experiments cannot provide direct evidences on generation and evolution of radicals in AOPs, while electron paramagnetic resonance (EPR) is a cutting-edge technology to identify radicals based on spectral characteristics. However, the complexity of EPR spectrum brings uncertainty and inconsistency to radical identification and mechanism clarification. This work presented a comprehensive study on identification of radicals by in-situ EPR analysis in four typical UV-based homogenous AOPs, including UV/H2O2, UV/peroxodisulfate (and peroxymonosulfate), UV/peracetic acid and UV/IO4- systems. Radical formation mechanism was also clarified based on EPR results. A reliable EPR method using organic solvents was proposed to identify alkoxy and alkyl radicals (CH3C(=O)OO·, CH3C(=O)O· and ·CH3) in UV/PAA system. Two activation pathways for radical production were proposed in UV/IO4- system, in which the produced IO3·, IO4·, ·OH and hydrated electron were precisely detected. It is interesting that addition of specific organic solvents can effectively identify oxygen-center and carbon-center radicals. A key parameter in EPR spectrum for 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin adduct, AH, is ranked as: ·CH3 (23 G) >·OH (15 G) >IO3· (12.9 G) >O2·- (11 G) ≥·OOH (9-11 G) ≥IO4· (9-10 G) ≥SO4·- (9-10 G) >CH3C(=O)OO· (8.5 G) > CH3C(=O)O· (7.5 G). This study will give a systematic method on identification of radicals in AOPs, and shed light on the insightful understanding of radical production mechanism.
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Affiliation(s)
- Long Chen
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Jun Duan
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China
| | - Penghui Du
- State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, PR China
| | - Weiliang Sun
- Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge 70803, LA, USA
| | - Bo Lai
- State Key Laboratory of Hydraulics and Mountain River Engineering, College of Architecture and Environment, Sichuan University, Chengdu 610065, PR China
| | - Wen Liu
- The Key Laboratory of Water and Sediment Sciences, Ministry of Education, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, PR China.
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New Insight into the Interactions of Arbutin with Mushroom Tyrosinase. Protein J 2021; 40:689-698. [PMID: 34047882 DOI: 10.1007/s10930-021-10004-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2021] [Indexed: 10/21/2022]
Abstract
As a safe substitute for hydroquinone, β-arbutin, a natural plant substance, and its synthetic counterpart, α-arbutin, are used in depigmentation formulations. However, there are debatable points regarding the impact of arbutin on tyrosinase and the pigmentation process. To shed light on this issue, the effects of Pyrus biossieriana leaves extract (PbLE) and β-arbutin, extracted from PbLE, on mushroom tyrosinase (MT) were comprehensively examined. The study was focused on cresolase activity as the characteristic reaction of a tyrosinase. Kinetics studies disclosed that β-arbutin can modulate MT monophenolase activity from inhibition to activation or vice versa. β-Arbutin inhibited L-tyrosine (LTy) oxidation at concentrations < 0.3 mM but it increased (more than 400%) the enzymatic oxidation of L-tyrosine at the concentrations > 0.3 mM. An opposite pattern (activation then inhibition) was observed when a synthetic substrate was used instead of LTy. Computational studies, focused on the heavy chain of MT, indicated that β-arbutin effect could be overruled by the enzyme's ability to provide the ligand with a non-specific binding site (MTPc). A plausible mechanism was presented to show the influence of MTPc on the substrate pose in the active site. The possible determinant correlation between the findings of this research and the current studies on human tyrosinase role in the pigmentation process has been presented.
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