Construction and Characterization of Glucose Enzyme Sensor Employing Engineered Water Soluble PQQ Glucose Dehydrogenase with Improved Thermal Stability

Abstract

In this study，we constmcted glucose enzyme sensors with increased thermal stability employing engineered pQQGDH-B．First，we demonstrated the enzyme glucose sensor employing an engineered PQQGDH-B，Ser231Lys， The residual activity after heat treatment at60℃for2hours of the enzyme electrode employed Ser231Lys was80％ of the initial acUvity，whereas the electro〔le employed native PQQGDH-B was30％，Second，we investigate(l the effect of cross-linking chemical modi五cation on the thermal stability of PQQGDH・B．The cross-1inked PQQGDHB had high therm田stabili取andtheha廿1ifedmeat55℃was63minwhereasthatofnative enzymewas4min．Fu控hemore，we demonstrated the Flow Injection Analysis(FIA)system for glucose measurement employed the cross-1inked PQQGDH-B．The high operational stability of this system showed the very stable responses(SD was within3％)for 100times of glucose injection． κ砂恥雇s Glucose Dehy(lrogenase，Pyrroloquinoline Quinone，Thermal Stability，Glucose Sensor l Introαuction Various glucose (1ehy〔lrogenases (GDHs)were reporte(i to possess pyn oloquinoline quinone (pQQ)as their prosthetic group．PQQGDHs have been given extensive attention as enzyme sensor constituents，because of their property of being oxygen in(1ependent．1・2)Although PQQGDHs have such superior prope血es，further improvement of the enzymatic properties is being required，considering an(1comparing with those of the most popular an(1m勾or enzyme utilize(l for glucose sensors，glucose oxi(1ase，θ．9．substrate speci且city and opera-