Takamitsu Kohzuma

Spectroscopic evidence for a copper-nitrosyl intermediate in nitrite reduction by blue copper-containing nitrite reductase

The reactions of nitrogen monoxide (NO) with the blue copper-containing nitrite reductases from Alcaligenes sp. NCIB 11015 and Achromobacter cycloclastes IAM 1013 were investigated spectroscopically. The electron paramagnetic resonance (EPR) signals of the blue coppers vanished in the presence of NO at 77 K, being fully restored by the removal of NO. The additions of NO to the enzyme solutions resulted in the substantial bleaching of the visible absorption bands at room temperature. The reactions were also completely reversible. These results suggest the formation of a cuprous nitrosyl complex (Cu+-NO+), which is likely the intermediate in the enzymatic nitrite reduction.

Novel spectroscopic aspects of type I copper in Hyphomicrobium nitrite reductase

Copper-containing nitrite reductase isolated from Hyphomicrobium sp. A 3151 has been characterized by electronic absorption, circular dichroism (CD) and electron paramagnetic resonance (EPR) spectroscopies. The visible absorption spectrum of Type I copper (blue copper) in the enzyme especially indicates novel features compared with those of Type I coppers in not only several nitrite reductases already reported but also small blue copper proteins. The EPR spectrum of Type I copper exhibits an axial symmetry.

Stability of ascorbate oxidase extracted from Cucurbita pepo

Abstract The physical and enzymic properties of ascorbate oxidase kept in saturated ammonium sulphate solution at 4° were examined before and after 10 months storage. There were no significant changes in behaviour on sodium dodecyl sulphate gels, in absorbtion spectra, circular dichroic spectra or EPR spectra during this time, nor in specific enzyme activity or Km. Such stored preparations are suitable for analytical examination in distant laboratories and possibly have commercial uses.

EPR Spectra of ferric cytochromes c′ from five strains of Achromobacterxylosoxidans at low temperature and their temperature dependence

The EPR spectra at low temperature (6 K) and their temperature dependence (10-93 K) for five ferric cytochromes c isolated from chemoheterotrophic bacteria, Achromobacter xylosoxidans NCIB 11015 (formerly Alcaligenes sp. NCIB 11015), GIFU 543, GIFU 1048, GIFU 1051, and GIFU 1764 are reported. The EPR spectral results indicate that the ground state of the heme iron(III) of cytochromes c from these chemoheterotrophic bacteria can appear to be in an admixed spin state which consists of predominant S = 5/2 with a slight S = 3/2 character. The EPR spectra were compared with those for ferric cytochromes c from photosynthetic bacteria and the other ferric hemoproteins.

Redox properties of thiolate-bridged binuclear nickel(II) complexes and correlation of their electronic spectra

SummaryThe redox properties of a series of thiolate-bridged binuclear nickel(II) complexes with NNS-tridentate and SNNS-tetradentate thiolic ligands have been studied by cyclic voltammetry. The first redox potential (E1/2=−0.63 to −0.95 Vversus Ag/AgCl) has a linear correlation with the absorption maxima of then

Preliminary crystallographic study of a pseudoazurin from methylotrophic bacterium, Methylobacterium extorquens AM1.

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Direct Electrochemistry of Nitrite Reductase from Achromobacter cycloclastes IAM 1013

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Direct Electrochemistry of Copper-Containing Nitrite Reductase from Achromobacter xylosoxidans NCIB 11015

In 3K + .C 14 H 3 N 2 O 8 3- .4H 2 O, all three carboxyl groups of pyrroloquinoline quinone (PQQ; 4, 5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid) are in anion form to neutralize the three potassium cations. Each of the three potassium ions is closely courdinated to polar atoms of the PQQ 3- ions and waters of crystallization. Noticeable structural features within the crystal unit are the stacking of the PQQ 3- ions and the extensive network of hydrogen-bonding interactions