scholarly journals Biochemical evidence of both copper chelation and oxygenase activity at the histidine brace

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Søren Brander ◽  
Istvan Horvath ◽  
Johan Ø. Ipsen ◽  
Ausra Peciulyte ◽  
Lisbeth Olsson ◽  
...  
Keyword(s):  
Biochemical Characterization ◽  
Copper Binding ◽  
Lytic Polysaccharide Monooxygenase ◽  
Copper Chelation ◽  
Biologically Relevant ◽  
Redox Active ◽  
Oxygenase Activity ◽  
Copper Site ◽  
Environment Control ◽  
Copper Binding Protein

Abstract Lytic polysaccharide monooxygenase (LPMO) and copper binding protein CopC share a similar mononuclear copper site. This site is defined by an N-terminal histidine and a second internal histidine side chain in a configuration called the histidine brace. To understand better the determinants of reactivity, the biochemical and structural properties of a well-described cellulose-specific LPMO from Thermoascus aurantiacus (TaAA9A) is compared with that of CopC from Pseudomonas fluorescens (PfCopC) and with the LPMO-like protein Bim1 from Cryptococcus neoformans. PfCopC is not reduced by ascorbate but is a very strong Cu(II) chelator due to residues that interacts with the N-terminus. This first biochemical characterization of Bim1 shows that it is not redox active, but very sensitive to H2O2, which accelerates the release of Cu ions from the protein. TaAA9A oxidizes ascorbate at a rate similar to free copper but through a mechanism that produce fewer reactive oxygen species. These three biologically relevant examples emphasize the diversity in how the proteinaceous environment control reactivity of Cu with O2.

Is increased redox-active iron in Alzheimer disease a failure of the copper-binding protein ceruloplasmin?

1999 ◽  
Vol 26 (11-12) ◽  
pp. 1508-1512 ◽  
Author(s):  
Rudy J Castellani ◽  
Mark A Smith ◽  
Akihiko Nunomura ◽  
Peggy L.R Harris ◽  
George Perry
Keyword(s):  
Alzheimer Disease ◽  
Binding Protein ◽  
Copper Binding ◽  
Active Iron ◽  
Redox Active ◽  
Copper Binding Protein

Electrochemical characterization of Cu(II) complexes of brain-related tau peptides

2021 ◽  
Vol 99 (7) ◽  
pp. 628-636
Author(s):  
Camilla Golec ◽  
Jose O. Esteves-Villanueva ◽  
Sanela Martic
Keyword(s):  
Metal Ions ◽  
Tau Protein ◽  
Metal Ion ◽  
Differential Pulse ◽  
Redox Couple ◽  
Peptide Sequence ◽  
Binding Studies ◽  
Biologically Relevant ◽  
Redox Active ◽  
Competition Binding

Metal ion dyshomeostasis plays an important role in diseases, including neurodegeneration. Tau protein is a known neurodegeneration biomarker, but its interactions with biologically relevant metal ions, such as Cu(II), are not fully understood. Herein, the Cu(II) complexes of four tau R peptides, based on the tau repeat domains, R1, R2, R3, and R4, were characterized by electrochemical methods, including cyclic voltammetry, square-wave voltammetry, and differential pulse voltammetry in solution under aerobic conditions. The current and potential associated with Cu(II)/(I) redox couple was modulated as a function of R peptide sequence and concentration. All R peptides coordinated Cu(II) resulting in a dramatic decrease in the current associated with free Cu(II), and the appearance of a new redox couple due to metallo–peptide complex. The metallo–peptide complexes were characterized by the irreversible redox couple at more positive potentials and slower electron-transfer rates compared with the free Cu(II). The competition binding studies between R peptides with Cu(II) indicated that the strongest binding affinity was observed for the R3 peptide, which contained 2 His and 1 Cys residues. The formation of complexes was also evaluated as a function of peptide concentration and in the presence of competing Zn(II) ions. Data indicate that all metallo–peptides remain redox active pointing to the potential importance of the interactions between tau protein with metal ions in a biological setting.

scholarly journals Biochemical characterization of the purple form of Marinobacter hydrocarbonoclasticus nitrous oxide reductase

2012 ◽  
Vol 367 (1593) ◽  
pp. 1204-1212 ◽  
Author(s):  
Simone Dell'Acqua ◽  
Sofia R. Pauleta ◽  
José J. G. Moura ◽  
Isabel Moura
Keyword(s):  
Nitrous Oxide ◽  
Redox State ◽  
Biochemical Characterization ◽  
Specific Activity ◽  
Active Species ◽  
Nitrous Oxide Reductase ◽  
Strictly Anaerobic ◽  
Prolonged Incubation ◽  
Redox Active ◽  
Marinobacter Hydrocarbonoclasticus

Nitrous oxide reductase (N 2 OR) catalyses the final step of the denitrification pathway—the reduction of nitrous oxide to nitrogen. The catalytic centre (CuZ) is a unique tetranuclear copper centre bridged by inorganic sulphur in a tetrahedron arrangement that can have different oxidation states. Previously, Marinobacter hydrocarbonoclasticus N 2 OR was isolated with the CuZ centre as CuZ*, in the [1Cu 2+ : 3Cu + ] redox state, which is redox inert and requires prolonged incubation under reductive conditions to be activated. In this work, we report, for the first time, the isolation of N 2 OR from M. hydrocarbonoclasticus in the ‘purple’ form, in which the CuZ centre is in the oxidized [2Cu 2+ : 2Cu + ] redox state and is redox active. This form of the enzyme was isolated in the presence of oxygen from a microaerobic culture in the presence of nitrate and also from a strictly anaerobic culture. The purple form of the enzyme was biochemically characterized and was shown to be a redox active species, although it is still catalytically non-competent, as its specific activity is lower than that of the activated fully reduced enzyme and comparable with that of the enzyme with the CuZ centre in either the [1Cu 2+ : 3Cu + ] redox state or in the redox inactive CuZ* state.

scholarly journals The Prion Protein is a Combined Zinc and Copper Binding Protein:  Zn2+Alters the Distribution of Cu2+Coordination Modes

2007 ◽  
Vol 129 (50) ◽  
pp. 15440-15441 ◽  
Author(s):  
Eric D. Walter ◽  
Daniel J. Stevens ◽  
Micah P. Visconte ◽  
Glenn L. Millhauser
Keyword(s):  
Prion Protein ◽  
Binding Protein ◽  
Copper Binding ◽  
Coordination Modes ◽  
Copper Binding Protein

scholarly journals A thylakoid membrane-bound and redox-active rubredoxin (RBD1) functions in de novo assembly and repair of photosystem II

2019 ◽  
Vol 116 (33) ◽  
pp. 16631-16640 ◽  
Author(s):  
José G. García-Cerdán ◽  
Ariel L. Furst ◽  
Kent L. McDonald ◽  
Danja Schünemann ◽  
Matthew B. Francis ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Thylakoid Membrane ◽  
De Novo Assembly ◽  
Biochemical Characterization ◽  
De Novo ◽  
Midpoint Potential ◽  
Photosynthetic Organisms ◽  
Redox Active ◽  
Photooxidative Damage

Photosystem II (PSII) undergoes frequent photooxidative damage that, if not repaired, impairs photosynthetic activity and growth. How photosynthetic organisms protect vulnerable PSII intermediate complexes during de novo assembly and repair remains poorly understood. Here, we report the genetic and biochemical characterization of chloroplast-located rubredoxin 1 (RBD1), a PSII assembly factor containing a redox-active rubredoxin domain and a single C-terminal transmembrane α-helix (TMH) domain. RBD1 is an integral thylakoid membrane protein that is enriched in stroma lamellae fractions with the rubredoxin domain exposed on the stromal side. RBD1 also interacts with PSII intermediate complexes containing cytochrome b559. Complementation of the Chlamydomonas reinhardtii (hereafter Chlamydomonas) RBD1-deficient 2pac mutant with constructs encoding RBD1 protein truncations and site-directed mutations demonstrated that the TMH domain is essential for de novo PSII assembly, whereas the rubredoxin domain is involved in PSII repair. The rubredoxin domain exhibits a redox midpoint potential of +114 mV and is proficient in 1-electron transfers to a surrogate cytochrome c in vitro. Reduction of oxidized RBD1 is NADPH dependent and can be mediated by ferredoxin-NADP+ reductase (FNR) in vitro. We propose that RBD1 participates, together with the cytochrome b559, in the protection of PSII intermediate complexes from photooxidative damage during de novo assembly and repair. This role of RBD1 is consistent with its evolutionary conservation among photosynthetic organisms and the fact that it is essential in photosynthetic eukaryotes.

scholarly journals Mapping hole hopping escape routes in proteins

2019 ◽  
Vol 116 (32) ◽  
pp. 15811-15816 ◽  
Author(s):  
Ruijie D. Teo ◽  
Ruobing Wang ◽  
Elizabeth R. Smithwick ◽  
Agostino Migliore ◽  
Michael J. Therien ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Protective Role ◽  
Residence Times ◽  
P450 Monooxygenase ◽  
Protection Mechanism ◽  
Biologically Relevant ◽  
Redox Active ◽  
Catalytic Sites ◽  
Benzylsuccinate Synthase

A recently proposed oxidative damage protection mechanism in proteins relies on hole hopping escape routes formed by redox-active amino acids. We present a computational tool to identify the dominant charge hopping pathways through these residues based on the mean residence times of the transferring charge along these hopping pathways. The residence times are estimated by combining a kinetic model with well-known rate expressions for the charge-transfer steps in the pathways. We identify the most rapid hole hopping escape routes in cytochrome P450 monooxygenase, cytochrome c peroxidase, and benzylsuccinate synthase (BSS). This theoretical analysis supports the existence of hole hopping chains as a mechanism capable of providing hole escape from protein catalytic sites on biologically relevant timescales. Furthermore, we find that pathways involving the [4Fe4S] cluster as the terminal hole acceptor in BSS are accessible on the millisecond timescale, suggesting a potential protective role of redox-active cofactors for preventing protein oxidative damage.

scholarly journals The copBL operon protects Staphylococcus aureus from copper toxicity: CopL is an extracellular membrane–associated copper-binding protein

2019 ◽  
Vol 294 (11) ◽  
pp. 4027-4044 ◽  
Author(s):  
Zuelay Rosario-Cruz ◽  
Alexander Eletsky ◽  
Nourhan S. Daigham ◽  
Hassan Al-Tameemi ◽  
G. V. T. Swapna ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Binding Protein ◽  
Copper Toxicity ◽  
Copper Binding ◽  
Copper Binding Protein
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