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Abstract：
The detection of a single-enzyme catalytic reaction by surfaced-enhanced Raman scattering (SERS) is presented by utilizing DNA origami-based plasmonic antennas. A single horseradish peroxidase (HRP) was accommodated on a DNA origami nanofork plasmonic antenna (DONA) containing gold nanoparticles, enabling the tracing of single-molecule SERS signals during the peroxide reduction reaction. This allows monitoring of the structure of a single enzymatic catalytic center and products under suitable liquid conditions. Herein, we demonstrate the chemical changes of HRP and the appearance of tetramethylbenzidine (TMB), which works as a hydrogen donor before and after the catalytic reaction. The results show that the iron in HRP adopts Fe4+ and low spin states with the introduction of H2O2, indicating compound-I formation. Density functional theory (DFT) calculations were performed for later catalytic steps to rationalize the experimental Raman/SERS spectra. The presented data provide several possibilities for tracking single biomolecules in situ during a chemical reaction and further developing plasmon-enhanced biocatalysis.
摘要：
通过利用基于DNA折纸的等离子天线，提出了通过表面增强拉曼散射（SERS）检测单酶催化反应的方法。将单个辣根过氧化物酶（HRP）容纳在含有金纳米颗粒的DNA折纸纳米叉等离子体天线（DONA）上，能够在过氧化物还原反应过程中跟踪单分子SERS信号。这允许在合适的液体条件下监测单个酶催化中心和产物的结构。在这里，我们证明了HRP的化学变化和四甲基联苯胺（TMB）的出现，在催化反应之前和之后作为氢供体。结果表明，HRP中的铁采用Fe4和低自旋态，并引入H2O2，表明化合物I的形成。进行密度泛函理论(DFT)计算用于后面的催化步骤,以使实验拉曼/SERS光谱合理化。所提供的数据提供了在化学反应期间原位跟踪单个生物分子并进一步开发等离子体激元增强的生物催化的几种可能性。
