Characterization of an Exopolygalacturonase from Leucoagaricus gongylophorus, the Symbiotic Fungus of Atta sexdens

The present study aimed to purify and characterize one polygalacturonase from L. gongylophorus (PGaseLg), the symbiotic fungus of Atta sexdens. The enzyme was isolated by salting out of crude extract followed by two chromatographic steps. PGaseLG was identified with MS analysis and molecular exclusion chromatography revealed the monomeric nature of a protein with an estimated molecular weight of about 39 kDa. PGaseLg has an optimum temperature of 60°C and optimum pH activity at 5.0. Using polygalacturonate as a substrate, the calculations of KM, Vmax and kcat were 0.65 mg·mL-1, 1800 μmol·min-1·mg-1 and 35.97 s-1, respectively. The enzyme was stable for more than 3 h at 50°C at pH 5.0; otherwise, at lower or higher pH values, the PGaseLg was less stable. The influence of several metals, EDTA and β-mercaptoethanol on enzyme activity was also determined. Thin layer chromatography (TLC) analyses indicated that PGaseLg is an exopolygalacturonase.