Dirigent Proteins and Dirigent Sites Explain the Mystery of Specificity of Radical Precursor Coupling in Lignan and Lignin Biosynthesis

The recent discovery of dirigent proteins ([Davin and Lewis, 1995][1]; [Davin et al., 1997][2]; [Gang et al., 1999][3]) gives a new perspective into how free radical coupling of monolignol plant phenols is controlled in planta to yield lignans and lignins. With the biochemical pathways to the