title: Repeated Random Mutagenesis of alpha-Amylase from Bacillus licheniformis for Improved pH Performance.
abstract: The alpha-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis alpha-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.
authors.affiliation: Department of Genetics, Centre for Excellence in Genomic Sciences, School of Biological Sciences, Madurai Kamaraj University, Madurai-625 021, India.
authors.forename: Ramachandran
authors.initials: R
authors.lastname: Priyadharshini
authors.forename: Shankar
authors.initials: S
authors.lastname: Manoharan
authors.forename: Devaraj
authors.initials: D
authors.lastname: Hemalatha
authors.forename: Paramasamy
authors.initials: P
authors.lastname: Gunasekaran
mesh_terms: D019943:Amino Acid Substitution; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics*; D004252:DNA Mutational Analysis; D004795:Enzyme Stability; D015723:Gene Library; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D016296:Mutagenesis; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D017422:Sequence Analysis, DNA; D000516:alpha-Amylases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D050505:Mutant Proteins; D000516:alpha-Amylases