A Novel α-Amylase from Bacillus mojavensis A21: Purification and Biochemical Characterization Noomen Hmidet & Hana Maalej & Anissa Haddar & Moncef Nasri Received: 12 August 2009 / Accepted: 28 December 2009 / Published online: 28 January 2010 # Springer Science+Business Media, LLC 2010 Abstract α-Amylase from Bacillus mojavensis A21 (BMA.2) was purified to homogeneity by ultrafiltration, Sephadex G-75 gel filtration and Sepharose mono Q anion exchange chromatography, with a 15.3-fold increase in specific activity and 11% recovery. The molecular weight of the BMA.2 enzyme was estimated to be 58 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel filtration. The optimum temperature and pH were 80°C and 6.5, respectively. BMA.2 belonged to the EDTA- sensitive α-amylase, but its activity was not stimulated by the presence of Ca 2+ ions. The major end-products of starch hydrolysis were maltohexaose, maltopentaose and maltotriose. The N-terminal amino acid sequence of the first ten amino acids of the purified α-amylase was ASVNGTLMQY. Compared to sequences of other amylases, the ten amino acid sequence contains Val at position 3, while amylases from Bacillus licheniformis NH1 and Bacillus sp. SG-1 have Leu and Thr at position 3, respectively. Keywords α-Amylase . B. mojavensis A21 . Purification . Biochemical characterization Introduction Amylases constitute a class of industrial enzymes having approximately 30% of the world enzyme production [1]. α-Amylases (EC 3.2.1.1, 1,4-α-D-glucan glucanohydrolase) were classified in family 13 of glycosyl hydrolases and hydrolyzes starch, glycogen and related polysaccharides by randomly cleaving internal α-1,4-glucosidic linkages to produce different sizes of oligosaccharides. They have diverse applications in a wide variety of industries such as food, fermentation, textile, paper, detergent, pharmaceutical and sugar industries [2]. Each application of α-amylase requires unique properties with respect to specificity, stability, temperature and pH dependence [3]. Although they can be derived Appl Biochem Biotechnol (2010) 162:1018–1030 DOI 10.1007/s12010-009-8902-7 N. Hmidet : H. Maalej : A. Haddar : M. Nasri (*) Laboratoire de Génie Enzymatique et de Microbiologie, Ecole Nationale d’Ingénieurs de Sfax, B.P. “W” 3038 Sfax, Tunisia e-mail: mon_nasri@yahoo.fr e-mail: moncef.nasri@enis.rnu.tn