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    A GFET Nitrile Sensor Using a Graphene-Binding Fusion Protein

    Year: 2022

    Journal: Adv. Funct. Mater., Volume 32, NOV

    Authors: Mohamed, Abubaker A.; Noguchi, Hironaga; Tsukiiwa, Mirano; Chen, Chen; Heath, Rachel S.; Mubarak, M. Qadri E.; Komikawa, Takumi; Tanaka, Masayoshi; Okochi, Mina; de Visser, Sam P.; Hayamizu, Yuhei; Blanford, Christopher F.

    Organizations: UK's Biotechnology and Biological Sciences Research Council (BBSRC) [BB/M011208/1]; UK's Higher Education Funding Council for England (HEFCE) N8 Research Partnership Catalyst fund

    Keywords: 2D materials; biosensing; computational chemistry; enzyme engineering; fibroin

    A new route to single-step and non-covalent immobilization of proteins on graphene is exemplified with the first biosensor for nitriles based on a graphene field-effect transistor (GFET). The biological recognition element is a fusion protein consisting of nitrile reductase QueF from Escherichia coli with an N-terminal self-assembling and graphene-binding dodecapeptide. Atomic force microscopy and analysis using a quartz crystal microbalance show that both the oligopeptide and the fusion protein incorporating it form a single adlayer of monomeric enzyme on graphene. The fusion protein has a 6.3-fold increase in binding affinity for benzyl cyanide (BnCN) versus wild-type QueF and a 1.4-fold increase for affinity for the enzyme's natural substrate preQ(0). Density functional theory analysis of QueF's catalytic cycle with BnCN shows similar transition-state barriers to preQ(0), but differences in the formation of the initial thioimidate covalent bonding ( increment G(double dagger) = 19.0 kcal mol(-1) for preQ(0) vs 27.7 kcal mol(-1) for BnCN) and final disassociation step ( increment G = -24.3 kcal mol(-1) for preQ(0) vs increment G = +4.6 kcal mol(-1) for BnCN). Not only do these results offer a single-step route to GFET modification, but they also present new opportunities in the biocatalytic synthesis of primary amines from nitriles.
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