DyP-like peroxidases of the jelly fungus Auricularia auricula-judae oxidize nonphenolic lignin model compounds and high-redox potential dyes.
The jelly fungus Auricularia auricula-judae produced an enzyme with manganese-independent peroxidase activity during growth on beech wood (approximately 300 U l(-1)). The same enzymatic activity was detected and produced at larger scale in agitated cultures comprising of liquid, plant-based media (e.g. tomato juice suspensions) at levels up to 8,000 U l(-1). Two pure peroxidase forms (A. auricula-judae peroxidase (AjP I and AjP II) could be obtained from respective culture liquids by three chromatographic steps. Spectroscopic and electrophoretic analyses of the purified proteins revealed their heme and peroxidase nature. The N-terminal amino acid sequence of AjP matched well with sequences of fungal enzymes known as "dye-decolorizing peroxidases". Homology was found to the N-termini of peroxidases from Marasmius scorodonius (up to 86%), Thanatephorus cucumeris (60%), and Termitomyces albuminosus (60%). Both enzyme forms catalyzed not only the conversion of typical peroxidase substrates such as 2,6-dimethoxyphenol and 2,2'-azino-bis(3-ethylthiazoline-6-sulfonate) but also the decolorization of the high-redox potential dyes Reactive Blue 5 and Reactive Black 5, whereas manganese(II) ions (Mn(2+)) were not oxidized. Most remarkable, however, is the finding that both AjPs oxidized nonphenolic lignin model compounds (veratryl alcohol; adlerol, a nonphenolic beta-O-4 lignin model dimer) at low pH (maximum activity at pH 1.4), which indicates a certain ligninolytic activity of dye-decolorizing peroxidases.
Liers
Christiane
C
Unit of Environmental Biotechnology, International Graduate School of Zittau, Markt 23, 02763 Zittau, Germany. liers@ihi-zittau.de
Bobeth
Caroline
C
Pecyna
Marek
M
Ullrich
René
R
Hofrichter
Martin
M
D001487:Basidiomycota / Q000201:enzymology*; D004396:Coloring Agents / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D004396:Coloring Agents; D005656:Fungal Proteins; D008031:Lignin; D009195:Peroxidase