title: Thermostabilization by Proline Substitution in an Alkaline, Liquefying α-Amylase from Bacillus sp. Strain KSM-1378.
abstract: α-Amylase (LAMY) from alkaliphilic Bacillus sp. strain KSM-1378 is a novel semi-alkaline enzyme which has 5-fold higher specific activity than that of a Bacillus licheniformis enzyme. The Arg124 in LAMY was replaced with proline by site-directed mutagenesis to increase thermostability of the enzyme. The wild-type and engineered LAMYs were very similar with respect to specific activity, kinetic values, pH-activity curve, and degree of inhibition by chelating reagents. Thermostability and structure stiffness of LAMYs as measured by fluorescence were increased by the proline substitution. The change of Arg124 to proline is assumed to stabilize the loop region involving aminio acid residues from 122 to 134. This is the first report that thermostability of an α-amylase is improved by proline substitution.
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: K
authors.initials: K
authors.lastname: Igarashi
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: T
authors.initials: T
authors.lastname: Ozawa
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: K
authors.initials: K
authors.lastname: Ikawa-Kitayama
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashi
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: H
authors.initials: H
authors.lastname: Araki
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: K
authors.initials: K
authors.lastname: Endo
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: H
authors.initials: H
authors.lastname: Hagihara
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: K
authors.initials: K
authors.lastname: Ozaki
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: S
authors.initials: S
authors.lastname: Kawai
authors.affiliation: a Tochigi Research Laboratories of Kao Corporation.
authors.forename: S
authors.initials: S
authors.lastname: Ito
keywords: Bacillus; alkaliphile; site-directed mutagenesis; thermostability; α-amylase