Resolving ligand hyperfine couplings of type 1 and 2 Cu(ii) in ascorbate oxidase by high field pulse EPRcorrelation spectroscopy

2010 ◽  
Vol 12 (1) ◽  
pp. 62-65 ◽  
Author(s):  
Alexey Potapov ◽  
Israel Pecht ◽  
Daniella Goldfarb
Keyword(s):  
High Field ◽  
Ascorbate Oxidase ◽  
Field Pulse ◽  
Hyperfine Couplings

scholarly journals Site-directed mutations in fungal laccase: effect on redox potential, activity and pH profile

1998 ◽  
Vol 334 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Feng XU ◽  
Randy M. BERKA ◽  
Jill A. WAHLEITHNER ◽  
Beth A. NELSON ◽  
Jeffrey R. SHUSTER ◽  
...  
Keyword(s):  
Redox Potential ◽  
Phenol Oxidase ◽  
Ascorbate Oxidase ◽  
Single Mutation ◽  
Redox Potentials ◽  
Wild Type ◽  
Ph Optimum ◽  
Ph Profile ◽  
Potential Activity

A Myceliophthora thermophila laccase and a Rhizoctonia solani laccase were mutated on a pentapeptide segment believed to be near the type-1 Cu site. The mutation L513F in Myceliophthora laccase and the mutation L470F in Rhizoctonia laccase took place at a position corresponding to the type-1 Cu axial methionine (M517) ligand in Zucchini ascorbate oxidase. The triple mutations V509L,S510E,G511A in Myceliophthora laccase and L466V,E467S,A468G in Rhizoctonia laccase involved a sequence segment whose homologue in ascorbate oxidase is flanked by the M517 and a type-1 Cu-ligating histidine (H512). The single mutation did not yield significant changes in the enzymic properties (including any significant increase in the redox potential of the type-1 Cu). In contrast, the triple mutation resulted in several significant changes. In comparison with the wild type, the Rhizoctonia and Myceliophthora laccase triple mutants had a phenol-oxidase activity whose pH optimum shifted 1 unit lower and higher, respectively. Although the redox potentials were not significantly altered, the Km, kcat and fluoride inhibition of the laccases were greatly changed by the mutations. The observed effects are interpreted as possible mutation-induced structural perturbations on the molecular recognition between the reducing substrate and laccase and on the electron transfer from the substrate to the type-1 Cu centre.

High field pulse magnet backed up with hydraulic pressure

1992 ◽  
Vol 177 (1-4) ◽  
pp. 27-30 ◽  
Author(s):  
A. Yamagishi ◽  
K. Tokumoto ◽  
K. Taniguchi ◽  
O. Kondo ◽  
M. Date
Keyword(s):  
High Field ◽  
Hydraulic Pressure ◽  
Field Pulse ◽  
Pulse Magnet

scholarly journals Electron spin echo spectroscopic studies of type 1 and type 2 copper in Rhus vernicifera laccase and in Cucurbita pepo medullosa ascorbate oxidase

FEBS Letters ◽  
1981 ◽  
Vol 136 (1) ◽  
pp. 80-84 ◽  
Author(s):  
L. Avigliano ◽  
J.L. Davis ◽  
M.T. Graziani ◽  
A. Marchesini ◽  
W.B. Mims ◽  
...  
Keyword(s):  
Electron Spin ◽  
Cucurbita Pepo ◽  
Spin Echo ◽  
Electron Spin Echo ◽  
Spectroscopic Studies ◽  
Ascorbate Oxidase ◽  
Rhus Vernicifera

scholarly journals Pulse-radiolysis studies on the interaction of one-electron reduced species with blue oxidases. Reduction of type-2-copper-depleted ascorbate oxidase

1984 ◽  
Vol 222 (1) ◽  
pp. 65-70 ◽  
Author(s):  
P O'Neill ◽  
E M Fielden ◽  
L Avigliano ◽  
G Marcozzi ◽  
A Ballini ◽  
...  
Keyword(s):  
Pulse Radiolysis ◽  
Ascorbate Oxidase ◽  
Native Protein ◽  
Rate Determining Step ◽  
Type 1 Copper ◽  
Intramolecular Transfer ◽  
Reducing Equivalents

The interaction of one-electron reduced metronidazole (ArNO2.-) with native and Type-2-copper-depleted ascorbate oxidase were studied in buffered aqueous solution at pH 6.0 and 7.4 by using the technique of pulse radiolysis. With ArNO2.-, reduction of Type 1 copper of the native enzyme and of the Type-2-copper-depleted ascorbate oxidase occurs via a bimolecular step and at the same rate. Whereas the native protein accepts, in the absence of O2, 6-7 reducing equivalents, Type-2-copper-depleted ascorbate oxidase accepts only 3 reducing equivalents with stoichiometric reduction of Type 1 copper. On reaction of O2.- with ascorbate oxidase under conditions of [O2.-] much greater than [ascorbate oxidase], removal of Type 2 copper results in reduction of all the Type 1 copper atoms, in contrast with reduction of the equivalent of only one Type 1 copper atom in the holoprotein. From observations at 610 nm, the rate of reduction of ascorbate oxidase by O2.- is not dependent on the presence of Type 2 copper. For the holoprotein, no significant optical-absorption changes were observed at 330 nm. It is proposed that electrons enter the protein via Type 1 copper in a rate-determining step followed by a fast intramolecular transfer of electrons within the protein. For the Type-2-copper-depleted protein, intramolecular transfer within the protein, however, is slow or does not occur. In the presence of O2, it is also suggested that re-oxidation of the partially reduced holoprotein occurs at steady state, as inferred from the observations at 330 nm and 610 nm. The role of Type 2 copper in ascorbate oxidase is discussed in terms of its involvement in redistribution of electrons within the protein or structural considerations.

Revisiting the nitrosyl complex of myoglobin by high-field pulse EPR spectroscopy and quantum mechanical calculations

2010 ◽  
Vol 12 (26) ◽  
pp. 7276 ◽  
Author(s):  
Marina Radoul ◽  
Mahesh Sundararajan ◽  
Alexey Potapov ◽  
Christoph Riplinger ◽  
Frank Neese ◽  
...  
Keyword(s):  
Epr Spectroscopy ◽  
High Field ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Nitrosyl Complex ◽  
Field Pulse ◽  
Pulse Epr

Charging and discharging studies in microwave capacitive switches under high field pulse discharges

2010 ◽  
Author(s):  
J. Jinyu Ruan ◽  
George Papaioannou ◽  
Nicolas Nolhier ◽  
David Tremouilles ◽  
Fabio Coccetti ◽  
...  
Keyword(s):  
High Field ◽  
Capacitive Switches ◽  
Field Pulse

scholarly journals Strain Sensors for High Field Pulse Magnets

2011 ◽  
pp. 1537-1551
Author(s):  
Christian Martinez ◽  
Yan Zheng ◽  
Daniel Easton ◽  
Kevin Farinholt ◽  
Gyuhae Park
Keyword(s):  
High Field ◽  
Strain Sensors ◽  
Field Pulse

scholarly journals Electron nuclear interactions in spin-3/2 color centers in silicon carbide: A high-field pulse EPR and ENDOR study

2021 ◽  
Vol 104 (12) ◽  
Author(s):  
Victor A. Soltamov ◽  
Boris V. Yavkin ◽  
Georgy V. Mamin ◽  
Sergei B. Orlinskii ◽  
Ilia D. Breev ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Field ◽  
Color Centers ◽  
Field Pulse ◽  
Nuclear Interactions ◽  
Pulse Epr
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