An exo-polygalacturonase (EC 3.2.1.15) was purified to apparent homogeneity from cultures of Fusarium oxysporum fsp.lycopersici on synthetic medium supplemented with citrus pectin, using preparative isoelectric focusing. The enzyme, denominated PG2, had an apparent A4, of 74 000 Da upon SDS-PAGE. The pI of the main PG2 isoform was 4.5, and pH and temperature optima were 5.0 and WC, respectively. PG2 hydrolyzed polygalacturonic acid in an exo-manner, as demonstrated by anaysis of degradation products. The enzyme was N-glycosylated. The N-terminal amino acid sequence, L-A-F-N-V-P-S-K-P-P, has no identity to other known polygalacturonases.