Polygalacturonases constitute the major part of pectinase preparations for many bioprocess purposes. Investigation on the digestive juice of snail Limicolaria flammea led to purification of two polygalacturonases named PG1 and PG2. Properties of these enzymes were examined to explore their potential in biotechnology applications. A three steps procedure including size exclusion, anion and cation exchange and hydrophobic interaction chromatography were used for purification. The enzymes PG1 and PG2 had native molecular weights of approximately 46 and 86 kDa, respectively and functioned both as monomeric structures. The purified polygalacturonases PG1 and PG2 showed optimum hydrolysis activities at 50°C in sodium acetate buffer pH 5.6. The common inhibitor of the two purified polygalacturonases activity were Mn2+, Ca2+, Zn2+, EDTA, SDS and L-cystein. NH3+  stimulate            the polygalacturonase PG1 while Ba2+ was an activator for polygalacturonase PG2. Substrate specificity indicated that these enzymes hydrolyse a broad range of pectin from different sources. The highest activity of PG1 was observed with apple pectin and lemon pectin while PG2 showed its highest activity with orange pectin. The catalytic efficiency of PG1 was highest for lemon pectin (0.125 µmol/min/mL) and orange pectin (0.124 µmol/min/mL). PG2 displayed highest catalytic efficiency (0.325 µmol/min/mL) towards orange pectin. These results suggest that orange and lemon pectin would be the potential physiological substrates of the two purified enzymes.

Polygalacturonases are extensively used in food industries for pectic substances degradation. In this paper, we investigate on thermal stability parameters of two Polygalacturonases previously isolated from digestive juice of the snail Limicolaria flammea for several industrial applications such as fruit juice clarification. Thermal inactivation was carried out in the temperature range of 55°C to 80°C from 15 to 120 min. All results were statistically analysed. The results shown that thermal inactivation of studied acid phosphatases follows first order kinetics. At their optimum temperatures, these enzymes showed high half-lives ranging from 462.06 to 630.10 min and D values from 1535.00 to 2093.64 min suggesting that these two enzymes had a large thermal stability. The high values of ΔG# (93.96 to 94.97 kJ/mol) reveal a better resistance to denaturation. The relatively high activation energies (from 120.35 to 129.13 kJ/mol) and average enthalpy values (from 117.67 to 126.44 kJ.mol−1) could corroborate the good stability of these biocatalyst. All these results suggest that Polygalacturonases from digestive juice of the snail Limicolaria flammea may be profitably exploited in future food industrial applications.