Efficient expression, purification, and characterization of a novel FAD-dependent glucose dehydrogenase from Aspergillus terreus in Pichia pastoris

J Microbiol Biotechnol. 2014 Nov 28;24(11):1516-24. doi: 10.4014/jmb.1401.01061.

Abstract

Flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) can utilize a variety of external electron acceptors and also has stricter substrate specificity than any other glucose oxidoreductases, which makes it the ideal diagnostic enzyme in the field of glucose biosensors. A gene coding for a hypothetical protein, similar to glucose oxidase and derived from Aspergillus terreus NIH2624, was overexpressed in Pichia pastoris GS115 under the control of an AOX1 promoter with a level of 260,000 U/l in the culture supernatant after fed-batch cultivation for 84 h. After a three-step purification protocol that included isopropanol precipitation, affinity chromatography, and a second isopropanol precipitation, recombinant FAD-GDH was purified with a recovery of 65%. This is the first time that isopropanol precipitation has been used to concentrate a fermentation supernatant and exchange buffers after affinity chromatography purification. The purified FAD-GDH exhibited a broad and diffuse band between 83 and 150 kDa. The recombinant FAD-GDH was stable across a wide pH range (3.5 to 9.0) with maximum activity at pH 7.5 and 55°C. In addition, it displayed very high thermal stability, with a half-life of 82 min at 60°C. These characteristics indicate that FAD-GDH will be useful in the field of glucose biosensors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aspergillus / enzymology
  • Aspergillus / genetics*
  • Electrophoresis, Polyacrylamide Gel
  • Fermentation
  • Flavin-Adenine Dinucleotide
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism*
  • Glucose 1-Dehydrogenase / chemistry
  • Glucose 1-Dehydrogenase / genetics
  • Glucose 1-Dehydrogenase / isolation & purification
  • Glucose 1-Dehydrogenase / metabolism*
  • Pichia / genetics*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism*

Substances

  • Fungal Proteins
  • Recombinant Proteins
  • Flavin-Adenine Dinucleotide
  • Glucose 1-Dehydrogenase