Purification and characteristics of a low-molecular-weight peptide possessing oxidative capacity for phenol from Phanerochaete chrysosporium

摘要

A new low-molecular-weight peptide with phenol oxidase activity, named PC factor, was isolated and purified from liquid culture of a white-rot basidiomycete Phanerochaete chrysosporium. Its molecular weight was about 600 Da estimated by gel-filtration. Three amino acids Glu, Gly and Val were detected in hydrolysate. Absorption peaks corresponding to amino acids and peptide were observed by UV and IR spectra analysis. And the signal of Ca of amino acid was also detected by ~(13)C-NMR method. PC factorhad high thermostability and remained active in weakly alkalescent pH range. It could chelate Fe~(3+) and reduce it to Fe~(2+), but no hydroxyl radical HO' could be detected during the reaction process. It could oxidize phenolic lignin-model compounds such as 2,6-dimethoxyphenol (2,6-DMP), 2,2'-azinobis (3-ethylbenzathiazoline-6-sulfinic acid) (ABTS) and syringaldazine in the absence of Mn~(2+) and H_2O_2. These characteristics differed greatly from those of manganese peroxi-dases. The oxidative catalysis of PC factor can be enhanced by certain metal ions such as Cu~(2+) and Mn~(2+) etc., and O+_2 molecule was necessary for this reaction. In summary, PC factor may function as an electron carrier in this novel oxidation-reduction system.