PURIFICATION AND CHARACTERIZATION OF A NEW ALPHA-AMYLASE OF INTERMEDIATE THERMAL-STABILITY FROM THE YEAST LIPOMYCES-KONONENKOAE

A new alpha-amylase from the extracellular culture of the yeast Lipomy ces kononenkoae CBS 5608 has been purified to homogeneity by ammonium sulphate treatment, affinity binding on cross-linked starch, and DEAE- Biogel A chromatography. The enzyme was monomeric, with an apparent M( r) of 76 kilodaltons, pI < 3.5, and optimum pH 4.5-5.0, and exhibited intermediate thermal stability. The temperature for optimal enzyme act ivity was 70 degrees C. It is a glycoprotein with both N- and O-linked sugars. Kinetic analyses indicate that the enzyme has an endoamylolyt ic mechanism. The k(M) for soluble starch was 0.80 g . L(-1) and the k (cat) was 622 . s(-1).