Physical and Chemical Properties of an Extracellular Low-Molecular-Weight Substance from the Brown-Rot Basidiomycete Fomitopsis palustris

摘要

A low-molecular-weight, extracellular substance with one-electron-oxidizing activity was isolated from wood-degrading cultures of the brown-rot basldiomycetous fungus Fomitopsis palustris. The substance was partially purified by acetone precipitation,gel-filtration chroma-tography on Sephadex G-50 and G-25, and DEAE-Sepharose ion-exchange chromatography. The partially-purified material was a glycopeptide composed of (549-6, w/w) protein and (42%, w/w) neutral carbohydrate, containing (0.06%, w/w) Fe(II) by weight. The molecular weight as estimated by Tricine-SDS-PAGE was 7,200-10,000; whereas the molecular weight as determined by size-exclusion or gel-filtration chromatography was 1,000-5,000. The glycopeptide reduced O_2> to H_2O_2 and Fe(III) toFe(II), and thus could generate hydroxyl radical via a Fenton reaction. One mg of the partially-purified glycopeptide reduced 1.7 μmol of Fe (III) to Fe(II) and contained at least 0,6 Mmol of a-hydroxyketone or endiol groups. Most of the α-hydro-xyketone groups were 1-amino-2-ketoses produced by the condensation of side-chain amino groups and carbohydrate aldehydes. The function of the glycopeptide in brown-rot decay is discussed.