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Triiodide reduction by cellobiose: quinone oxidoreductase of Phanerochaete chrysosporium
Author(s) -
Bao Wenjun,
Renganathan V.
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)80242-u
Subject(s) - phanerochaete , chrysosporium , cellobiose , chemistry , quinone , oxidoreductase , cellobiose dehydrogenase , stereochemistry , biochemistry , enzyme , cellulase
Cellobiose: quinone oxidoreductase (CBQase) in the presence of cellobiose inhibits peroxidase‐catalyzed oxidation of iodide to triiodide (I 3 , − ). This inhibition is due to the two‐electron reduction of I − 3 by CBQase. The apparent K m of I − 3 for this reaction is 120 μM and the specific activity is 57 μmol·min −1 ·mg −1 . A proposed mechanism for I − 3 reduction by CBQase involves initial reduction of the flavin moiety by cellobiose to produce a dihydroflavin. This is followed by the substitution of one of the iodine atoms of I − 3 at the C(4a)‐position of dihydroflavin to generate C(4a)‐iododihydroflavin and two iodide ions. The C(4a)‐iododihydroflavin eliminates HI to regenerate the oxidized CBQase.