Construction and characterization of glucose enzyme sensor employing engineered water soluble PQQ glucose dehydrogenase with improved thermal stability

In this study, we constructed 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 at 60 degreesC for 2 hours of the enzyme electrode employed Ser231Lys was 80% of the initial activity, whereas the electrode employed native PQQGDH-B was 30%. Second, we investigated the effect of cross-linking chemical modification on the thermal stability of PQQGDH-B. The cross-linked PQQGDH-B had high thermal stability and the half life time at 55 degreesC was 63 min whereas that of native enzyme was 4 min. Furthermore, we demonstrated the Flow Injection Analysis (FIA) system for glucose measurement employed the cross-linked PQQGDH-B. The high operational stability of this system showed the very stable responses (SD was within 3%) for Ino times of glucose injection.