Removal of H(2)O(2), oxidation of toxic reductants, biosynthesis and degradation of lignin, suberization, auxin catabolism, response to environmental stresses such as wounding, pathogen attack and oxidative stress. These functions might be dependent on each isozyme/isoform in each plant tissue (By similarity). Has a high preference for hydroxycinnamates as substrates. Substrate preference is ferulic acid > p-coumaric acid > N-acetyl tyrosine methyl ester > N-acetyl-tyrosine > tyrosine > catechol > Gly-Tyr-Gly. May be involved in the formation of diferulate linkages in the plant cell wall (PubMed:16650004). 2 a phenolic donor + H2O2 = 2 a phenolic radical donor + 2 H2O Binds 1 heme b (iron(II)-protoporphyrin IX) group per subunit. Binds 2 calcium ions per subunit. Optimum pH is 3.8 with 2.2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) as substrate, 5.5 with ferulic acid as substrate, and 6.5 with N-acetyl-L-tyrosine as substrate. Loss of activity at temperature above 55 degrees Celsius. In the presence of excess calcium, full activity is kept at 65 degrees Celsius for 90 minutes. Monomer. Present in germinated and ungerminated grain, seedlings, and leaves and stem of the mature plant. The proportions of glycoforms I and II are 35% and 65% respectively. Deglycosylated form. Glycoform I. Glycoform II. Belongs to the peroxidase family. Classical plant (class III) peroxidase subfamily.