title: A chimeric α-amylase engineered from Bacillus acidicola and Geobacillus thermoleovorans with improved thermostability and catalytic efficiency.
abstract: The α-amylase (Ba-amy) of Bacillus acidicola was fused with DNA fragments encoding partial N- and C-terminal region of thermostable α-amylase gene of Geobacillus thermoleovorans (Gt-amy). The chimeric enzyme (Ba-Gt-amy) expressed in Escherichia coli displays marked increase in catalytic efficiency [K cat: 4 × 10(4) s(-1) and K cat/K m: 5 × 10(4) mL(-1) mg(-1) s(-1)] and higher thermostability than Ba-amy. The melting temperature (T m) of Ba-Gt-amy (73.8 °C) is also higher than Ba-amy (62 °C), and the CD spectrum analysis revealed the stability of the former, despite minor alteration in secondary structure. Langmuir-Hinshelwood kinetic analysis suggests that the adsorption of Ba-Gt-amy onto raw starch is more favourable than Ba-amy. Ba-Gt-amy is thus a suitable biocatalyst for raw starch saccharification at sub-gelatinization temperatures because of its acid stability, thermostability and Ca(2+) independence, and better than the other known bacterial acidic α-amylases.
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Parashar
authors.affiliation: Department of Microbiology, University of Delhi South Campus, Benito Juarez Road, New Delhi, 110021, India. tsnarayana@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Satyanarayana
mesh_terms: D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D055162:Biocatalysis; D004795:Enzyme Stability / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D056506:Geobacillus / Q000201:enzymology* / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D050506:Mutant Chimeric Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D017433:Protein Structure, Secondary / Q000235:genetics; D013213:Starch / Q000378:metabolism; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D050506:Mutant Chimeric Proteins; D013213:Starch; D000516:alpha-Amylases
keywords: Acid stability; Catalytic efficiency; Chimeric α-amylase; Raw starch; Thermostability