The measurement of time evolution of electrochemical impedance enables enzymatic kinetic studies in real-time, and obviates the need of using additional reagents as in many popular spectroscopic methods. This can eventually lead to the development of enzyme biosensors. We have used the urea–urease system as a model for this study. The usage of a free enzyme (without any immobilization steps) in this work makes the technique very simple and unique for electrochemical measurement on urease. The impedance vs . time measurement of urease exhibits Michaelis–Menten (MM) behaviour with the MM constant ( $$K_{\mathrm {{m}}}$$ K m ) of 0.8 mM and maximum velocity ( $$V_{\mathrm {{max}}}$$ V max ) of $$5000\hbox { ohms min}^{{{-1}}}$$ 5000 ohms min - 1 . This $$K_{\mathrm {{m}}}$$ K m value closely matched the one, which is obtained from the conventional colorimetric method (values). The enzyme kinetics was performed in a standard three-electrode system and reproduced in a fabricated mini electrochemical cell in an Eppendorf tube, which could pave the way for the development of impedimetric biosensors for a variety of enzyme systems, especially the ones for which spectrometric techniques cannot be readily applied.

中文翻译：

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尿素-尿素酶系统酶动力学的交流阻抗测量：阻抗生物传感器模型

电化学阻抗随时间变化的测量可以实时进行酶动力学研究，并且不需要像许多流行的光谱方法一样使用额外的试剂。这最终会导致酶生物传感器的发展。我们使用尿素-尿素酶系统作为本研究的模型。在这项工作中使用游离酶（没有任何固定步骤）使得该技术对于脲酶的电化学测量非常简单和独特。阻抗 vs 。脲酶的时间测量表现出 Michaelis-Menten (MM) 行为，MM 常数 ( $$K_{\mathrm {{m}}}$$ K m ) 为 0.8 mM 和最大速度 ( $$V_{\mathrm {{max }}}$$ V max ) $$5000\hbox { ohms min}^{{{-1}}}$$ 5000 ohms min - 1 。这个 $$K_{\mathrm {{m}}}$$ K m 值非常匹配，这是从传统的比色法（值）获得的。酶动力学在标准的三电极系统中进行，并在 Eppendorf 管中制造的微型电化学池中重现，这可以为开发用于各种酶系统的阻抗生物传感器铺平道路，尤其是那些需要光谱技术的酶系统。不能轻易应用。