-!- The enzyme from white rot basidiomycetes is involved in the oxidative degradation of lignin. -!- The enzyme oxidizes a bound Mn(2+) ion to Mn(3+) in the presence of hydrogen peroxide. -!- The product, Mn(3+), is released from the active site in the presence of a chelator (mostly oxalate and malate) that stabilizes it against disproportionation to Mn(2+) and insoluble Mn(4+). -!- The complexed Mn(3+) ion can diffuse into the lignified cell wall, where it oxidizes phenolic components of lignin and other organic substrates. -!- It is inactive with veratryl alcohol or nonphenolic substrates.