Bailey David M, Hennig Andreas, Uzunova Vanya D, Nau Werner M
School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
Chemistry. 2008;14(20):6069-77. doi: 10.1002/chem.200800463.
The coupling of an enzymatic transformation with dynamic host-guest exchange allows the unselective binding of macrocycles to be used for highly selective analyte sensing. The resulting supramolecular tandem enzyme assays require the enzymatic substrate and its corresponding product to differ significantly in their affinity for macrocycles, for example, cation receptors, and to show a differential propensity to displace a fluorescent dye from its host-guest complex. The enzymatic transformation results in a concomitant dye displacement that can be accurately followed by optical spectroscopy, specifically fluorescence. By exploiting this label-free continuous enzyme assay principle with the fluorescent dye Dapoxyl and the macrocyclic host cucurbit[7]uril, a multiparameter sensor array has been designed, which is capable of detecting the presence of amino acids (e.g. histidine, arginine, lysine, and tyrosine) and their decarboxylases. Only in the presence of both, the particular amino acid and the corresponding decarboxylase, is the amine or diamine product formed. These products are more highly positively charged than the substrate, have a higher affinity for the macrocycle and, therefore, displace the dye from the complex. The extension of the high selectivity and muM sensitivity of the tandem assay principle has also allowed for the accurate measurement of D-lysine enantiomeric excesses of up to 99.98 %, as only the L-enantiomer is accepted by the enzyme as a substrate and is converted to the product that is responsible for the observed fluorescence signal.
酶促转化与动态主客体交换的结合，使得大环化合物的非选择性结合可用于高选择性的分析物传感。由此产生的超分子串联酶分析要求酶底物及其相应产物对大环化合物（例如阳离子受体）的亲和力有显著差异，并表现出从其主客体复合物中置换荧光染料的不同倾向。酶促转化会导致染料随之被置换，这可以通过光谱学，特别是荧光准确地跟踪。通过利用荧光染料达波昔（Dapoxyl）和大环主体葫芦[7]脲的这种无标记连续酶分析原理，设计了一种多参数传感器阵列，它能够检测氨基酸（例如组氨酸、精氨酸、赖氨酸和酪氨酸）及其脱羧酶的存在。只有在特定氨基酸和相应脱羧酶都存在的情况下，才会形成胺或二胺产物。这些产物比底物带更高的正电荷，对大环化合物具有更高的亲和力，因此会从复合物中置换染料。串联分析原理的高选择性和微摩尔灵敏度的扩展，还使得能够准确测量高达99.98%的D-赖氨酸对映体过量，因为只有L-对映体被酶作为底物接受并转化为产生观察到的荧光信号的产物。
