A peptide-mediated and hydroxyl radical HO*-involved oxidative degradation of cellulose by brown-rot fungi.

A special low-molecular-weight peptide named Gt factor, was isolated and purified from the extracellular culture of brown-rot fungi Gloeophyllum trabeum via gel filtration chromatography and HPLC. It has been shown to reduce Fe3+ to Fe2+. Electron paramagnetic resonance (EPR) spectroscopy revealed Gt factor was able to drive H2O2 generation via a superoxide anion O2*- intermediate and mediate the formation of hydroxyl radical HO* in the presence of O2. All the results indicated that Gt factor could oxidize the cellulose, disrupt the inter- and intrahydrogen bonds in cellulose chains by a HO*-involved mechanism. This resulted in depolymerization of the cellulose, which made it accessible for further enzymatic hydrolysis.