Thermophilic glucokinase-based sensors for the detection of various saccharides and glycosides

Glucokinase from Bacillus stearothermophilus has an equal specificity for α- and β-anomers of glucose and a higher selectivity for glucose than other glucokinases. It seems to be useful for construction of multienzymatic saccharide sensors. Novel saccharide and glucosidic glycoside sensors were developed using the glucokinase, saccharide hydrolases and an ion sensitive field effect transistor (ISFET). An approach to amperometric biosensor was also developed using glucose-6-phosphate dehydrogenase (G6PDH) from B. stearothermophilus and a porous platinum black electrode. For example, by combining with thermostable β-d-glucosidase, the sensor responds to some β-d-glucosidic glycosides such as salicin, esculin and some saccharides such as cellobiose and lactose at 50 °C. Furthermore, thermophilic G6PDH immobilized onto the porous Pt black electrode worked as an amperometric biosensor for glucose-6-phosphate. These approaches revealed potential applications of the glucokinase to amperometric biosensors.