A pectate lyase from a deep subseafloor Georgenia muralis with unusual molecular characteristics

A novel pectate lyase of a deep subseafloor bacterium, Georgenia muralis strain JAM 3H7-3 (JCM19733), was purified to homogeneity from a culture broth by an anion exchange chromatography, followed by heat treatment of the enzyme solution at 60 °C for 30 min, and a gel filtration in the presence of SDS. The purified enzyme (Pel-S2) had a molecular mass of ~51 kDa by SDS-PAGE and ~75 kDa by gel filtration. In contrast, without heat treatment, the purified enzyme in SDS sample buffer was found to consist of 23- and 23.5-kDa polypeptides by SDS-PAGE. The enzyme was gradually inactivated by heat treatment with and without SDS in parallel with a shift of polypeptides molecular masses from 23 and 23.5 to 51 kDa on SDS-PAGE. Pel-S2 degraded pectate optimally at pH 10 in a glycine buffer and temperature of 50 °C. The enzyme showed relatively broad substrate specificity toward pectic acid and pectin.