Nano-Encapsulation of Glucose Oxidase Dimer by Graphene
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Nano-Encapsulation of Glucose Oxidase Dimer by Graphene Umesh Ghoshdastider1‡§, Rongliang Wu1‡§, Bartosz Trzaskowski2, Krzysztof Mlynarczyk2, Przemyslaw Miszta2, Manickam Gurusaran3,4, Sowmya Viswanathan5, Venkatesan Renugopalakrishnan4, Slawomir Filipek2*
1
International Institute of Molecular and Cell Biology, Warszawa, Poland Faculty of Chemistry, University of Warsaw, Warszawa, Poland 3 Supercomputer Education and Research Centre, Indian Institute of Science, Bangalore, India 4 Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA 5 Wellesley Hospital/Partners Healthcare System, Newton, Massachusetts, USA. 2
‡
These authors contributed equally.
§
Present Addresses: UG: Institute of Molecular and Cell Biology (A*STAR), Singapore. RW: College of Material Science and Engineering, Donghua University, Shanghai, China. * Corresponding Author
ABSTRACT Using all-atom molecular dynamics simulations in water environment, it was possible to demonstrate spontaneous and tight encapsulation of glucose oxidase (GOx) dimer by graphene 7 nm x 7 nm sheets linked together by linkers of different width and forming a flower-like or cross-like shapes. The partially overlapping graphene sheets compacted the structure of GOx dimer, bringing the monomers much closer to one another. We found that the most complete wrapping of the enzyme was achieved for the cross-like graphene. Encapsulation can be a useful way to obtain a large contact surface. However, an exceptionally tight binding by the graphene can also influence the positions of amino acids in the enzyme binding site resulting in less efficient catalytic reaction. Furthermore, such extensive encapsulation could block the access of the substrate to the active site of the enzyme. Contrary, a partial encapsulation by graphene using nano-sheets caused only small distortions of GOx structure while the contact surface with graphene was high. INTRODUCTION Glucose oxidase (GOx) is a glycoprotein that catalyzes the conversion of -D-glucose to -gluconolactone and hydrogen peroxide in the presence of oxygen. In 1962, Clark and Lyons [1] demonstrated that the presence of glucose in blood plasma could be detected by the change in the potential of the electrode adjacent to GOx during catalysis of glucose. The oxidation overpotential of the electrode reaction can be reduced by modifying the electrode with graphene or other 2D material to facilitate a direct electron transport from the GOx active site being a redox center and containing FAD (flavin adenine dinucleotide). Graphene, because of its properties as being strong, flexible, transparent and highly conductive, could be relatively advantageous for sensing compared to other carbon nanomaterials [2]. Furthermore, nowadays, graphene can be fabricated in many shapes and sizes, including recently introduced growth in lithographically patterned hexagonal boron nitride atomic layers [3], which makes it highly suitable for encapsulation. Graphene, a two-dimensional, single-atom-thick crystalline material has fascinated a
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