title: Cloning, heterologous expression, and enzymatic characterization of a thermostable glucoamylase from Talaromyces emersonii.
abstract: The gene encoding a thermostable glucoamylase from Talaromyces emersonii was cloned and, subsequently, heterologously expressed in Aspergillus niger. This glucoamylase gene encodes a 618 amino acid long protein with a calculated molecular weight of 62,827Da. T. emersonii glucoamylase fall into glucoside hydrolase family 15, showing approximately 60% sequence similarity to glucoamylase from A. niger. The expressed enzyme shows high specific activity towards maltose, isomaltose, and maltoheptaose, having 3-6-fold elevated k(cat) compared to A. niger glucoamylase. T. emersonii glucoamylase showed significantly improved thermostability with a half life of 48h at 65 degrees C in 30% (w/v) glucose, compared to 10h for glucoamylase from A. niger. The ability of the glucoamylase to hydrolyse amylopectin at 65 degrees C is improved compared to A. niger glucoamylase, giving a significant higher final glucose yield at elevated temperatures. The increased thermal stability is thus reflected in the industrial performance, allowing T. emersonii glucoamylase to operate at a temperature higher than the A. niger enzyme.
mesh_terms: D001234:Aspergillus niger / Q000235:genetics*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D015870:Gene Expression; D005087:Glucan 1,4-alpha-Glucosidase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005936:Glucans / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007534:Isomaltose / Q000378:metabolism; D007700:Kinetics; D008320:Maltose / Q000378:metabolism; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins; D013379:Substrate Specificity; D032901:Talaromyces / Q000201:enzymology* / Q000235:genetics; D013696:Temperature
chemical_list: D005936:Glucans; D011993:Recombinant Fusion Proteins; C031146:maltoheptaose; D007534:Isomaltose; D008320:Maltose; D005087:Glucan 1,4-alpha-Glucosidase