NAD-dependent fon-nate dehydrogenase (FDH, EC 1.2.1.2.) was purified 34-fold with 5.8% yield as an electrophoretically homogeneous protein from the white-rot fungus Ceriporiopsis subvermispora. The native enzyme has a molecular mass of 84 kDa consisting of two identical subunits as a homodimer. The K-m values for formate and NAD were found to be 2.5 mM and 28 mu M, respectively, at the optimum pH 6.5. The enzyme activity was inhibited by NADH, ADP, and ATR The kinetic analysis indicated that the enzyme reaction proceeded by the ordered Bi Bi mechanism. Oxalate was found to be catabolized by mediations of oxalate decarboxylase (ODC, EC 4.1.1.2) and FDH during the vegetative growth of C. subvermispora, while it was oxidized by oxalate oxidase (OXO, EC 1.2.3.4) at the later stage of the cultivation. A possible role of the two-oxalate decomposing systems with ODC and OXO was discussed in relation to carbon metabolism of lignin-degrading basidiomycetes. (c) 2005 Elsevier Inc. All rights reserved.