Purification and characterization of extracellular pectate lyase from Bacillus subtilis

Bacillus subtilis strain SO113 secretes a pectate lyase which is produced during the exponential death phase of growth, just before sporulation. This extracellular pectate lyase, which produces unsaturated products from polygalacturonate, was purified 35-fold from the culture supernatant of Bacillus subtilis by a CM Sephadex chromatography. It has an isoelectric point of about 9.6 and an Mr of 42 000. Optimum activity occured at pH 8.4 and at 42°C. Calcium has a stimulative effect on the enzyme activity while EDTA leads to enzyme inactivation. The pectate lyase has a specific activity of 131 μmol of aldehyde groups per min and per mg of protein. The Km of the purified enzyme for polygalacturonic acid was 0.862 g·l1 and the Vmax for polygalacturonic acid hydrolysis was 1.475 μmol of unsaturated products per min and per mg of protein. By using monoclonal antibodies raised against Erwinia chrysanthemi 3937 pectate lyases, it was shown that pectate lyases b and c of this strain are immunologically closely related to the Bacillus subtilis pectate lyase.