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Okurita M, Suzuki N, Loew N, Yoshida H, Tsugawa W, Mori K, Kojima K, Klonoff DC, Sode K. Engineered fungus derived FAD-dependent glucose dehydrogenase with acquired ability to utilize hexaammineruthenium(III) as an electron acceptor. Bioelectrochemistry 2018; 123:62-69. [PMID: 29727765 DOI: 10.1016/j.bioelechem.2018.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 04/09/2018] [Accepted: 04/09/2018] [Indexed: 11/30/2022]
Abstract
Fungal FAD-dependent glucose dehydrogenases (FADGDHs) are considered to be superior enzymes for glucose sensor strips because of their insensitivity to oxygen and maltose. One highly desirable mediator for enzyme sensor strips is hexaammineruthenium(III) chloride because of its low redox potential and high storage stability. However, in contrast to glucose oxidase (GOx), fungal FADGDH cannot utilize hexaammineruthenium(III) as electron acceptor. Based on strategic structure comparison between FADGDH and GOx, we constructed a mutant of Aspergillus flavus-derived FADGDH, capable of utilizing hexaammineruthenium(III) as electron acceptor: AfGDH-H403D. In AfGDH-H403D, a negative charge introduced at the pathway-entrance leading to the FAD attracts the positively charged hexaammineruthenium(III) and guides it into the pathway. The corresponding amino acid in wild-type GOx is negatively charged, which explains the ability of GOx to utilize hexaammineruthenium(III) as electron acceptor. Electrochemical measurements showed a response current of 46.0 μA for 10 mM glucose with AfGDH-H403D and hexaammineruthenium(III), similar to that with wild-type AfGDH and ferricyanide (47.8 μA). Therefore, AfGDH-H403D is suitable for constructing enzyme electrode strips with hexaammineruthenium(III) chloride as sole mediator. Utilization of this new, improved fungal FADGDH should lead to the development of sensor strips for blood glucose monitoring with increased accuracy and less stringent packing requirements.
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Affiliation(s)
- Madoka Okurita
- Department of Industrial Technology and Innovation, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Nanami Suzuki
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Noya Loew
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan; Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC 27599, USA
| | - Hiromi Yoshida
- Life Science Research Center and Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan
| | - Wakako Tsugawa
- Department of Industrial Technology and Innovation, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan; Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Kazushige Mori
- Ultizyme International Ltd., 1-13-16, Minami, Meguro, Tokyo 152-0013, Japan
| | - Katsuhiro Kojima
- Ultizyme International Ltd., 1-13-16, Minami, Meguro, Tokyo 152-0013, Japan
| | - David C Klonoff
- Diabetes Research Institute, Mills-Peninsula Medical Center, 100 South San Mateo Drive, San Mateo, CA 94401, USA
| | - Koji Sode
- Department of Industrial Technology and Innovation, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan; Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan; Joint Department of Biomedical Engineering, The University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC 27599, USA; Ultizyme International Ltd., 1-13-16, Minami, Meguro, Tokyo 152-0013, Japan.
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Loew N, Tsugawa W, Nagae D, Kojima K, Sode K. Mediator Preference of Two Different FAD-Dependent Glucose Dehydrogenases Employed in Disposable Enzyme Glucose Sensors. SENSORS 2017; 17:s17112636. [PMID: 29144384 PMCID: PMC5712826 DOI: 10.3390/s17112636] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/13/2017] [Accepted: 11/14/2017] [Indexed: 02/07/2023]
Abstract
Most commercially available electrochemical enzyme sensor strips for the measurement of blood glucose use an artificial electron mediator to transfer electrons from the active side of the enzyme to the electrode. One mediator recently gaining attention for commercial sensor strips is hexaammineruthenium(III) chloride. In this study, we investigate and compare the preference of enzyme electrodes with two different FAD-dependent glucose dehydrogenases (FADGDHs) for the mediators hexaammineruthenium(III) chloride, potassium ferricyanide (the most common mediator in commercial sensor strips), and methoxy phenazine methosulfate (mPMS). One FADGDH is a monomeric fungal enzyme, and the other a hetero-trimeric bacterial enzyme. With the latter, which contains a heme-subunit facilitating the electron transfer, similar response currents are obtained with hexaammineruthenium(III), ferricyanide, and mPMS (6.8 µA, 7.5 µA, and 6.4 µA, respectively, for 10 mM glucose). With the fungal FADGDH, similar response currents are obtained with the negatively charged ferricyanide and the uncharged mPMS (5.9 µA and 6.7 µA, respectively, for 10 mM glucose), however, no response current is obtained with hexaammineruthenium(III), which has a strong positive charge. These results show that access of even very small mediators with strong charges to a buried active center can be almost completely blocked by the protein.
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Affiliation(s)
- Noya Loew
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu, Tokyo 183-8538, Japan.
| | - Wakako Tsugawa
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu, Tokyo 183-8538, Japan.
| | - Daichi Nagae
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
| | - Katsuhiro Kojima
- Ultizyme International Ltd., 1-13-16, Minami, Meguro, Tokyo 152-0013, Japan.
| | - Koji Sode
- Department of Biotechnology and Life Science, Graduate School of Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588, Japan.
- Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu, Tokyo 183-8538, Japan.
- Ultizyme International Ltd., 1-13-16, Minami, Meguro, Tokyo 152-0013, Japan.
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