Stereoselective bimolecular phenoxy radical coupling by an auxiliary (dirigent) protein without an active center

Laurence B. Davin, Huai Bin Wang, Anastasia L. Crowell, Diana L. Bedgar, Diane M. Martin, Simo Sarkanen, Norman G. Lewis

Research output: Contribution to journalArticlepeer-review

490 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)362-366
Number of pages5
JournalScience
Volume275
Issue number5298
DOIs
StatePublished - Jan 17 1997

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