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Oxidative Cleavage of Cellobiose by Lytic Polysaccharide Monooxygenase (LPMO)-Inspired Copper Complexes
[Image: see text] The potentially tridentate ligand bis[(1-methyl-2-benzimidazolyl)ethyl]amine (2BB) was employed to prepare copper complexes [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) as bioinspired models of lytic polysaccharide copper-dependent monooxygenase (LPMO) enzymes. Solid-state c...
Autores principales: | , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2019
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648734/ https://www.ncbi.nlm.nih.gov/pubmed/31460171 http://dx.doi.org/10.1021/acsomega.9b00785 |
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author | Neira, Andrea. C. Martínez-Alanis, Paulina R. Aullón, Gabriel Flores-Alamo, Marcos Zerón, Paulino Company, Anna Chen, Juan Kasper, Johann B. Browne, Wesley R. Nordlander, Ebbe Castillo, Ivan |
author_facet | Neira, Andrea. C. Martínez-Alanis, Paulina R. Aullón, Gabriel Flores-Alamo, Marcos Zerón, Paulino Company, Anna Chen, Juan Kasper, Johann B. Browne, Wesley R. Nordlander, Ebbe Castillo, Ivan |
author_sort | Neira, Andrea. C. |
collection | PubMed |
description | [Image: see text] The potentially tridentate ligand bis[(1-methyl-2-benzimidazolyl)ethyl]amine (2BB) was employed to prepare copper complexes [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) as bioinspired models of lytic polysaccharide copper-dependent monooxygenase (LPMO) enzymes. Solid-state characterization of [(2BB)Cu(I)]OTf revealed a Cu(I) center with a T-shaped coordination environment and metric parameters in the range of those observed in reduced LPMOs. Solution characterization of [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) indicates that [(2BB)Cu(II)(H(2)O)(2)](2+) is the main species from pH 4 to 7.5; above pH 7.5, the hydroxo-bridged species [{(2BB)Cu(II)(H(2)O)(x)}(2)(μ-OH)(2)](2+) is also present, on the basis of cyclic voltammetry and mass spectrometry. These observations imply that deprotonation of the central amine of Cu(II)-coordinated 2BB is precluded, and by extension, amine deprotonation in the histidine brace of LPMOs appears unlikely at neutral pH. The complexes [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) act as precursors for the oxidative degradation of cellobiose as a cellulose model substrate. Spectroscopic and reactivity studies indicate that a dicopper(II) side-on peroxide complex generated from [(2BB)Cu(I)]OTf/O(2) or [(2BB)Cu(II)(H(2)O)(2)](OTf)(2)/H(2)O(2)/NEt(3) oxidizes cellobiose both in acetonitrile and aqueous phosphate buffer solutions, as evidenced from product analysis by high-performance liquid chromatography-mass spectrometry. The mixture of [(2BB)Cu(II)(H(2)O)(2)](OTf)(2)/H(2)O(2)/NEt(3) results in more extensive cellobiose degradation. Likewise, the use of both [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) with KO(2) afforded cellobiose oxidation products. In all cases, a common Cu(II) complex formulated as [(2BB)Cu(II)(OH)(H(2)O)](+) was detected by mass spectrometry as the final form of the complex. |
format | Online Article Text |
id | pubmed-6648734 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-66487342019-08-27 Oxidative Cleavage of Cellobiose by Lytic Polysaccharide Monooxygenase (LPMO)-Inspired Copper Complexes Neira, Andrea. C. Martínez-Alanis, Paulina R. Aullón, Gabriel Flores-Alamo, Marcos Zerón, Paulino Company, Anna Chen, Juan Kasper, Johann B. Browne, Wesley R. Nordlander, Ebbe Castillo, Ivan ACS Omega [Image: see text] The potentially tridentate ligand bis[(1-methyl-2-benzimidazolyl)ethyl]amine (2BB) was employed to prepare copper complexes [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) as bioinspired models of lytic polysaccharide copper-dependent monooxygenase (LPMO) enzymes. Solid-state characterization of [(2BB)Cu(I)]OTf revealed a Cu(I) center with a T-shaped coordination environment and metric parameters in the range of those observed in reduced LPMOs. Solution characterization of [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) indicates that [(2BB)Cu(II)(H(2)O)(2)](2+) is the main species from pH 4 to 7.5; above pH 7.5, the hydroxo-bridged species [{(2BB)Cu(II)(H(2)O)(x)}(2)(μ-OH)(2)](2+) is also present, on the basis of cyclic voltammetry and mass spectrometry. These observations imply that deprotonation of the central amine of Cu(II)-coordinated 2BB is precluded, and by extension, amine deprotonation in the histidine brace of LPMOs appears unlikely at neutral pH. The complexes [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) act as precursors for the oxidative degradation of cellobiose as a cellulose model substrate. Spectroscopic and reactivity studies indicate that a dicopper(II) side-on peroxide complex generated from [(2BB)Cu(I)]OTf/O(2) or [(2BB)Cu(II)(H(2)O)(2)](OTf)(2)/H(2)O(2)/NEt(3) oxidizes cellobiose both in acetonitrile and aqueous phosphate buffer solutions, as evidenced from product analysis by high-performance liquid chromatography-mass spectrometry. The mixture of [(2BB)Cu(II)(H(2)O)(2)](OTf)(2)/H(2)O(2)/NEt(3) results in more extensive cellobiose degradation. Likewise, the use of both [(2BB)Cu(I)]OTf and [(2BB)Cu(II)(H(2)O)(2)](OTf)(2) with KO(2) afforded cellobiose oxidation products. In all cases, a common Cu(II) complex formulated as [(2BB)Cu(II)(OH)(H(2)O)](+) was detected by mass spectrometry as the final form of the complex. American Chemical Society 2019-06-20 /pmc/articles/PMC6648734/ /pubmed/31460171 http://dx.doi.org/10.1021/acsomega.9b00785 Text en Copyright © 2019 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes. |
spellingShingle | Neira, Andrea. C. Martínez-Alanis, Paulina R. Aullón, Gabriel Flores-Alamo, Marcos Zerón, Paulino Company, Anna Chen, Juan Kasper, Johann B. Browne, Wesley R. Nordlander, Ebbe Castillo, Ivan Oxidative Cleavage of Cellobiose by Lytic Polysaccharide Monooxygenase (LPMO)-Inspired Copper Complexes |
title | Oxidative Cleavage of Cellobiose by Lytic Polysaccharide
Monooxygenase (LPMO)-Inspired Copper Complexes |
title_full | Oxidative Cleavage of Cellobiose by Lytic Polysaccharide
Monooxygenase (LPMO)-Inspired Copper Complexes |
title_fullStr | Oxidative Cleavage of Cellobiose by Lytic Polysaccharide
Monooxygenase (LPMO)-Inspired Copper Complexes |
title_full_unstemmed | Oxidative Cleavage of Cellobiose by Lytic Polysaccharide
Monooxygenase (LPMO)-Inspired Copper Complexes |
title_short | Oxidative Cleavage of Cellobiose by Lytic Polysaccharide
Monooxygenase (LPMO)-Inspired Copper Complexes |
title_sort | oxidative cleavage of cellobiose by lytic polysaccharide
monooxygenase (lpmo)-inspired copper complexes |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648734/ https://www.ncbi.nlm.nih.gov/pubmed/31460171 http://dx.doi.org/10.1021/acsomega.9b00785 |
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