Abstract
Bacillus macerans produced an extracellular endo-pectate lyase when cultivated with grated potato tuber. The enzyme activity was markedly activated by 1 mM calcium or manganese ion, but completely inactivated by ethylenediaminetetraacetate (EDTA). The activity was maximum at pH 9.0 and 60°C. The enzyme activity was stable up to 50°C and 55°C for 10min at pH 9.0 in the absence and presence of calcium ion, respectively, and between pH 6.5 and 9.5 for 2 hr at 37°C. The enzyme had a molecular weight of 35, 000 and a pI of 10.3. The Michaelis constant and maximum reaction velocity of the enzyme for polypectate were 0.11% and 74μmiol of unsaturated galacturonate formed per min per mg protein, respectively. The enzyme also attacked pectin that contained 4.3% methoxyl groups. The enzyme was stable in 100 mM ammonium chloride buffer (pH 9.0) for a month at 10°C, but 70% of its activity was lost in 20 mM ammonium chloride buffer (pH 9.0) after 24 hr at 10°C.
