Institute for Bioscience and Biotechnology Research and Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA.
ACS Chem Biol. 2013 Apr 19;8(4):716-24. doi: 10.1021/cb300605s. Epub 2013 Jan 24.
Phenolics are among the most abundant redox-active organics in nature, but the intractability of phenolic materials (e.g., melanin) has precluded study of their biological activities and functions. Previous studies demonstrated that a model abiotic catecholic matrix can rapidly exchange electrons with biological oxidants and reductants without the need for enzymes. Here, a novel electrochemically based reverse engineering approach was employed to probe redox interactions between this model matrix and a population of bacteria. Specifically, this method employs redox-active natural products (e.g., pyocyanin) to shuttle electrons between the bacteria and the abiotic matrix, and imposed oscillating potential inputs to engage redox-cycling mechanisms that switch the matrix's redox state. The oscillating output currents were observed to be amplified, gated, and partially rectified, while the overall magnitude and direction of electron flow across the matrix depended on the biological and environmental context. These response characteristics support hypotheses that natural phenolic materials may be integral to extracellular electron transport for processes that include anaerobic respiration, redox signaling, and redox-effector action.
酚类化合物是自然界中最丰富的氧化还原活性有机物质之一，但由于酚类物质（如黑色素）难以处理，其生物活性和功能一直未能得到研究。先前的研究表明，一种模型非生物儿茶酚基质可以无需酶的作用即可快速与生物氧化剂和还原剂交换电子。在这里，采用了一种新颖的基于电化学的反向工程方法来探测该模型基质与细菌群体之间的氧化还原相互作用。具体而言，该方法利用氧化还原活性天然产物（如绿脓菌素）在细菌和非生物基质之间穿梭电子，并施加振荡电势输入，以激活氧化还原循环机制，从而改变基质的氧化还原状态。观察到振荡输出电流被放大、门控和部分整流，而横跨基质的电子流的整体幅度和方向取决于生物和环境背景。这些响应特征支持以下假设，即天然酚类物质可能是包括厌氧呼吸、氧化还原信号传递和氧化还原效应子作用在内的细胞外电子传递过程的组成部分。
