TY - JOUR
T1 - Stereoselective bimolecular phenoxy radical coupling by an auxiliary (dirigent) protein without an active center
AU - Davin, Laurence B.
AU - Wang, Huai Bin
AU - Crowell, Anastasia L.
AU - Bedgar, Diana L.
AU - Martin, Diane M.
AU - Sarkanen, Simo
AU - Lewis, Norman G.
PY - 1997/1/17
Y1 - 1997/1/17
N2 - The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol.
AB - The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselves and thus some other agent must exist. A 78-kilodalton protein has been isolated that, in the presence of an oxidase or one electron oxidant, effects stereoselective bimolecular phenoxy radical coupling in vitro. Itself lacking a catalytically active (oxidative) center, its mechanism of action is presumed to involve capture of E-coniferyl alcohol-derived free-radical intermediates, with consequent stereoselective coupling to give (+)-pinoresinol.
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U2 - 10.1126/science.275.5298.362
DO - 10.1126/science.275.5298.362
M3 - Article
C2 - 8994027
AN - SCOPUS:0031031957
SN - 0036-8075
VL - 275
SP - 362
EP - 366
JO - Science
JF - Science
IS - 5298
ER -