"There is one thing even more vital to science than intelligent methods;and that is, the sincere desire to find out the truth, whatever it may be."
Charles Sanders Pierce
Heme peroxidases are commercially important as controlled and powerful oxidants. We are especially interested in the oxidation reactions that cause polymerization and depolymerization of lignin (left). Lignin is the recalcitrant phenylpropanoid polymer that lends hardness and water resistance to wood. The polymer is formed extracellularly by radical condensation reactions in the plant cell wall. Lignin is an important barrier to efficient use of biomass. Lignin removal is a critical step in liberating cellulose (for paper or ethanol production) from woody material and represents a key step in the earth's carbon cycle. The extracellular fungal peroxidases, lignin peroxidase and manganese peroxidase (shown below in red and blue, respectively) catalyze the initial oxidation reactions required to degrade lignin in nature. (see publications list)
Despite extensive biophysical study of a few select enzymes such as manganese peroxidase, the biological functions of most peroxidases remain unproven. A large number of plant peroxidases have been identified by sequence homology; however, most have unknown function. The disconnect between the biochemical and genetic data is enormous. The Arabidopsis genome encodes over 70 putative extracellular peroxidases. We are currently working on identifying the biochemical function of these important enzymes. In addition, we are interested in the evolutionary relationship between plant and fungal peroxidases and their involvement in the evolution of lignin formation in plants. This understanding will help us to better engineer plants for use as feedstock and biofuels.
