Characterization of a new endo-type polyM-specific alginate lyase from Pseudomonas sp

An alginate lyase gene, algA, encoding a new poly β-d-mannuronate (polyM)-specific alginate lyase AlgA, was cloned from Pseudomonas sp. E03. The recombinant AlgA with (His)₆-tag, consisting of 364 amino acids (40.4 kDa),was purified using Ni–NTA Sepharose. The purified lyase had maximal activity (222 EU/mg) at pH 8 and 30 °C and also maintained activity between pH 7–9 and below 45 °C. It exclusively and endolytically depolymerized polyM by β-elimination into oligosaccharides with degrees of polymerization (DP) of 2–5. Due to its high substrate specificity, AlgA could be a valuable tool for production of polyM oligosaccharides with low DP and for determining the fine structure of alginate.