• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.156-159
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• 2018

We developed a glucose sensor using glucose dehydrogenase flavin adenine dinucleotide (GDH-FAD). The structure of the three-layer glucose sensor was simplified, in which a single-layer design was used to lower the unit cost, and GDH-FAD was used to increase the measurement reliability. GDH-FAD has less impact on the 20 interfering substances that affect blood glucose measurement, such as galactose and maltose compared to glucose oxidase (GOD), and is not affected by the oxygen saturation; therefore, it is possible to measure both arterial or venous blood and thus less susceptibility to hematocrit. In this study, we developed a single-layer glucose sensor strip with low hematocrit effect using the GDH-FAD enzyme, and measured and evaluated the performance.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1516-1524
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• 2014

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 $55^{\circ}C$. In addition, it displayed very high thermal stability, with a half-life of 82 min at $60^{\circ}C$. These characteristics indicate that FAD-GDH will be useful in the field of glucose biosensors.