Fig. 4
From: Lignin engineering through laccase modification: a promising field for energy plant improvement
Monolignols and a lignin polymer model. a Primary lignin monomers: p-coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. The three monolignols differ in the degree of methoxylation, and are catalyzed by peroxidase and/or laccases to form the corresponding p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin unit, respectively. b A polymer model depicting the general feature of lignin. The model is constructed by Accelrys Draw 4.2 with two H units, six G units and eight S units, showing the main linkage types. The bolded bonds are formed in the radical coupling reactions. This is only a model, and do not imply any primary structure or composition of plant lignin