Abstract
Plant peroxidases form a numerous multigenic family in higher plants. We have surveyed peroxidase genes in the Populus trichocarpa database and found at least 79 sequences encode complete peroxidase protein with manual annotation. Diversity of peroxidase isoenzymes was investigated from genome structure and amino acid sequences. The coding sequence of the majority of the peroxidase genes are disrupted by three introns. P. trichocarpa PO44 and PO85 were suggested to be an ancestral poplar peroxidase genes by the phylogenetic tree analysis. Within the protein structure of peroxidases, observed changes of highly conserved residue may cause significant change in enzyme kinetics, substrate specificities, and functions. An unique peroxidase isoenzyme from P. alba, CWPO-C, has broad substrate versatility, and Tyr-74 and/or Tyr-177 located on the protein surface were postulated as its oxidastion site. P. trichocarpa PO13, that is ortholog of CWPO-C, was the sole peroxidase possessing both Tyrosine residues in P. trichocarpa.
