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Dopaquinone hydroxylation through topaquinone cofactor in copper amine oxidases: A simplified chemical model
Author(s) -
Rinaldi Andrea C.,
Rescigno Antonio,
Sollai Francesca,
Soddu Giulia,
Curreli Nicoletta,
Rinaldi Augusto,
FinazziAgrò Alessandro,
Sanjust Enrico
Publication year - 1996
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549600201682
Subject(s) - hydroxylation , cofactor , chemistry , amine gas treating , copper , active site , hydroxide , residue (chemistry) , tyrosine , stereochemistry , catalysis , organic chemistry , biochemistry , enzyme
A simple model, 4‐tert‐butyl‐1,2‐benzoquinone, was chosen to study the hydroxylation step of the tyrosine‐derived Dopaquinone residue at the active site of copper amine oxidases in the self‐catalytic generation of the Topaquinone cofactor. This hydroxylation step was studied both in the presence and absence of free copper(II), and was found to be dependent on pH value but not on the presence of metal ions. It is therefore proposed that, hydroxide ion and not water should be the true reactive species in this key biosynthetic step of the Topaquinone cofactor, and that the active site Cu2+ is implied, at this point of cofactor biosynthesis, in the quinonisation of Topa rather than in the hydroxylation of Dopaquinone.