Isolation and characterization of a novel thermostable α-amylase from Korean pine seeds

Amylases have significant importance in broad industrial application including bio-ethanol production. Although amylases are widely distributed in microbes, plants and animals, it has been sought for new amylases from various sources with special industrial potential. In this study we firstly isolated and characterized a novel thermostable α-amylase from Korean pine seed. Enzyme was purified to homogeneity level with purification fold of 1286.1 using several techniques such as self-precipitation, (NH₄)₂SO₄ fractionation, DEAE anion exchange and starch affinity chromatography. The purified α-amylase showed two bands in SDS-PAGE with molecular weight of 44 and 45 kDa. The apparent molecular weight of native enzyme was calculated to be 46.7 kDa. Internal peptide sequencing confirmed that the purified α-amylase was a novel enzyme. The optimum pH and temperature for enzyme activity were pH 4.5 and 65 °C, respectively. This enzyme was fully stable for 48 h at 50 °C and retained 80% activity up to 96 h. The K_m and V_max were 0.84 mg/ml and 3.71 μmol/min, respectively. On the basis of high thermal stability and a broad range of pH stability, the pine seed α-amylase showed a good prospect of industrial application.