Supplementary Material for: Purification and Biochemical and Kinetic Properties of an Endo-Polygalacturonase from the Industrial Fungus Aspergillus sojae

An endo-polygalacturonase secreted by Aspergillus sojae was
characterized after being purified to homogeneity from submerged
cultures with orange peel as the sole carbon source by gel filtration
and ion-exchange chromatographies. According to SDS-PAGE and analytical
isoelectric focusing analyses, the enzyme presents a molecular weight of
47 kDa and pI value of 4.2. This enzyme exhibits considerable stability
under highly acidic to neutral conditions (pH 1.5-6.5) and presents a
half-life of 2 h at 50°C. Besides its activity towards pectin and
polygalacturonic acid, the enzyme displays pectin-releasing activity,
acting best in a pH range of 3.3-5.0. Thin-layer chromatographic
analysis revealed that tri-galacturonate is the main enzymatic end
product of polygalacturonic acid hydrolysis, indicating that it is an
endo-polygalacturonase. The enzyme exhibits Michaelis-Menten kinetics,
with KM and VMAX values of 0.134 mg/mL and 9.6 µmol/mg/min, respectively, and remained stable and active in the presence of SO2, ethanol, and various cations assayed except Hg2+.