Electroactive centers in Euphorbia latex and lentil [Lens esculenta] seedling amine oxidases

The electrochemical behavior of redox centers in the active site of amine oxidases from lentil seedlings and Euphorbia characias latex was investigated using a mercury film electrode. Tyrosine-derived 6-hydroxydopa quinone (TPQ) and copper ions in the active site are redox centers of these amine oxi...

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Bibliographic Details
Published in:Bioscience, biotechnology, and biochemistry biotechnology, and biochemistry, 2008-01, Vol.72 (1), p.29-36
Main Authors: Heli, H.(University of Tehran (Iran)), Amani, M, Moosavi-Movahedi, A.A, Jabbari, A, Floris, G, Mura, A
Format: Article
Language:English
Subjects:
AMINE OXIDASE
Amine Oxidase (Copper-Containing) - chemistry
Amine Oxidase (Copper-Containing) - metabolism
AMINE OXYDASE
Amino Acid Oxidoreductases - chemistry
Amino Acid Oxidoreductases - metabolism
Amino Acid Sequence
AMINO OXIDASA
Binding Sites
Biological and medical sciences
CHEMICAL REACTIONS
Copper - metabolism
Dihydroxyphenylalanine - analogs & derivatives
Dihydroxyphenylalanine - analysis
Electrochemistry
ELECTRODE
ELECTRODES
ELECTRODOS
EUPHORBIA
Euphorbia - enzymology
Euphorbia latex
Fundamental and applied biological sciences. Psychology
Kinetics
LATEX
LENS CULINARIS
Lens Plant - enzymology
lentil seedlings
mercury film electrode
Molecular Sequence Data
Oxidation-Reduction
Plant Proteins - chemistry
Plant Proteins - metabolism
PLANTULAS
PLANTULE
REACCIONES QUIMICAS
REACTION CHIMIQUE
SEEDLINGS
Seedlings - enzymology
topa quinone
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Summary:The electrochemical behavior of redox centers in the active site of amine oxidases from lentil seedlings and Euphorbia characias latex was investigated using a mercury film electrode. Tyrosine-derived 6-hydroxydopa quinone (TPQ) and copper ions in the active site are redox centers of these amine oxidases. The enzymes undergo two reduction processes at negative potentials related to the reduction of the TPQ cofactor to the corresponding hydroquinones and the reduction of copper ions, (Cu(II) - Cu(I)). Copper depleted enzymes, prepared by reduction with dithionite followed by dialysis against cyanide, undergo only one reduction process. Nyquist diagrams, recorded at potentials corresponding to the reduction of cofactors as dc-offset, represent charge transfer impedance followed by a Warburg-type line at low frequencies, indicating the occurrence of a diffusion controlled process in the rate-limiting step of the reduction process.
ISSN:0916-8451
1347-6947
DOI:10.1271/bbb.70299