Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
J Am Chem Soc. 2022 Jun 1;144(21):9465-9471. doi: 10.1021/jacs.2c02695. Epub 2022 May 18.
Signal transduction mechanisms are key to living systems. Cells respond to signals by changing catalytic activity of enzymes. This signal responsive catalysis is crucial in the regulation of (bio)chemical reaction networks (CRNs). Inspired by these networks, we report an artificial signal responsive system that shows signal-induced temporary catalyst activation. We use an unstable signal to temporarily activate an out of equilibrium CRN, generating transient host-guest complexes to control catalytic activity. Esters with favorable binding toward the cucurbit[7]uril (CB[7]) supramolecular host are used as temporary signals to form a transient complex with CB[7], replacing a CB[7]-bound guest. The esters are hydrolytically unstable, generating acids and alcohols, which do not bind to CB[7], leading to guest reuptake. We demonstrate the feasibility of the concept using signal-controlled temporary dye release and reuptake. The same signal controlled system was then used to tune the reaction rate of aniline catalyzed hydrazone formation. Varying the ester structure and concentration gave access to different catalyst liberation times and free catalyst concentration, regulating the overall reaction rate. With temporary signal controlled transient complex formation we can tune the kinetics of a second chemical reaction, in which the signal does not participate. This system shows promise for building more complex nonbiological networks, to ultimately arrive at signal transduction in organic materials.
信号转导机制是生命系统的关键。细胞通过改变酶的催化活性来响应信号。这种对信号响应的催化作用对于（生物）化学反应网络（CRN）的调控至关重要。受这些网络的启发，我们报告了一种人工信号响应系统，该系统显示出信号诱导的临时催化剂激活。我们使用不稳定的信号来临时激活非平衡 CRN，生成瞬态主体 - 客体配合物以控制催化活性。具有与葫芦[7]脲（CB[7]）超分子主体有利结合的酯类用作临时信号，与 CB[7]形成瞬态复合物，取代 CB[7]结合的客体。酯类在水解上不稳定，生成不与 CB[7]结合的酸和醇，导致客体再摄取。我们使用信号控制的临时染料释放和再摄取来证明该概念的可行性。然后，使用相同的信号控制体系来调节苯胺催化腙形成的反应速率。改变酯的结构和浓度可以获得不同的催化剂释放时间和游离催化剂浓度，从而调节整体反应速率。通过临时信号控制瞬态复合物形成，我们可以调节第二个不参与信号的化学反应的动力学。该系统有望构建更复杂的非生物网络，最终实现有机材料中的信号转导。
