title: Biochemical characterization of an extracellular polyextremophilic α-amylase from the halophilic archaeon Halorubrum xinjiangense.
abstract: An extracellular haloalkaliphilic thermostable α-amylase producing archaeon was isolated from the saltwater Lake Urmia and identified as Halorubrum xinjiangense on the basis of morphological, biochemical, and molecular properties. The enzyme was purified to an electrophoretically homogenous state by 80 % cold ethanol precipitation, followed by affinity chromatography. The concentrated pure amylase was eluted as a single peak on fast protein liquid chromatography. The molecular mass of the purified enzyme was about 60 kDa, with a pI value of 4.5. Maximum amylase activity was at 4 M NaCl or 4.5 M KCl, 70 °C, and pH 8.5. The K m and V max of the enzyme were determined as 3.8 mg ml(-1) and 12.4 U mg(-1), respectively. The pure amylase was stable in the presence of SDS, detergents, and organic solvents. In addition, the enzyme (20 U) hydrolyzed 69 % of the wheat starch after a 2-h incubation at 70 °C in an aqueous/hexadecane two-phase system.
authors.affiliation: Department of Pharmaceutical Biotechnology, Faculty of Pharmacy and Biotechnology Research Center, Tehran University of Medical Sciences, P.O. Box 14155-6451, 14174 Tehran, Iran.
authors.forename: Mahsa
authors.initials: M
authors.lastname: Moshfegh
authors.forename: Ahmad Reza
authors.initials: AR
authors.lastname: Shahverdi
authors.forename: Gholamreza
authors.initials: G
authors.lastname: Zarrini
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Faramarzi
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry*; D004795:Enzyme Stability; D055352:Halorubrum / Q000201:enzymology*; D006868:Hydrolysis; D007700:Kinetics; D013213:Starch / Q000737:chemistry; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D019843:Archaeal Proteins; D013213:Starch; D000516:alpha-Amylases