Covalent Attachment of Ferrocene to Soybean Peroxidase Glycans: Electron Transfer Mediation to Redox Enzymes

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• 作者：Neil Carolan ; Robert J. Forster ; Ciará ; n Ó ; 'Fá ; gá ; in
• 刊名：Bioconjugate Chemistry
• 出版年：2007
• 出版时间：March 2007
• 年：2007
• 卷：18
• 期：2
• 页码：524 - 529
• 全文大小：85K
• 年卷期：v.18,no.2(March 2007)
• ISSN：1520-4812

文摘

The electrochemical properties of native soybean peroxidase (SBP) and of SBP modified with covalently attachedferrocene electron-transfer mediators within microcavities etched at the tip of 25 s/entities/mgr.gif">m radius platinum microelectrodesare reported. The microcavities incorporate approximately 50 fmol of SBP. In the microcavity, native SBP undergoesa relatively fast reduction but a very slow oxidation. Ferrocene mediators have been attached to the SBP glycans(Fc-SBP) (approximately 1.5 ferrocene mediators per SBP molecule). Cyclic voltammetry reveals that thesecenters are capable of mediating the reduction of oxidized SBP and increase the rate of heterogeneous electrontransfer between the enzyme and the electrode by >10-fold. Micromolar concentrations of H₂O₂ chemically oxidizethe SBP and Fc-SBP systems leading to an electrocatalytic reduction at approximately -0.1 V. Successive additionsof 2.5 s/entities/mgr.gif">mol of H₂O₂ at a constant applied potential of -0.1 V gave a steady-state constant current of approximately60 nA within 20 s. The steady-state current increased linearly with peroxide concentration for 2.5 s/entities/le.gif"> [H₂O₂] s/entities/le.gif">42 s/entities/mgr.gif">M. Ferrocene-modified SBP shows an approximately 3-fold increase in the sensitivity of the steady-statecurrent response to successive additions of hydrogen peroxide compared to the native enzyme. This observationindicates increased turnover of the redox enzyme per unit time in the presence of the covalently attached ferrocenemediators.