Thermodynamic characterization of a highly thermoactive extracellular pectate lyase from a new isolate Bacillus pumilus DKS1

An extracellular pectate lyase (EC 4.2.2.2) was purified from the culture filtrate of a newly isolated Bacillus pumilus DKS1 grown in pectin containing medium. Using ion-exchange and gel filtration chromatography, this enzyme was purified and found to have a molecular weight of around 35kDa. The purified enzyme exhibited maximal activity at a temperature of 75 degrees C and pH 8.5. The presence of 1mM calcium and manganese enhanced pectate lyase activity and was strongly inhibited by zinc, nickel and EDTA. The thermal inactivation studies revealed an entropy-enthalpy compensation pattern below a critical temperature. The alkaliphilicity and high thermostability of this pectate lyase may have potential implications in fibre degumming.