Temporal pH waveforms generated in an enzymatic reaction network in batch and cell-sized microcompartments

Investigating and designing reaction networks and their emergent phenomena are the backbone of systems chemistry. Designing chemical oscillators in homogeneous systems utilizing enzymatic reactions is challenging due to the consumption of the substrates over one reaction cycle. Here, we show that an antagonistic enzymatic reaction network comprising urea-urease and ester-esterase reactions can generate temporal pH variations in a batch. We developed a coupled reaction kinetic model to elucidate the mechanism that accurately captures the experimentally observed pH variation over time. To demonstrate the remarkable potential of the enzymatic reaction network, we expanded on this discovery by generating front propagation and presenting several applications by coupling this enzymatic reaction network to fuel pH-dependent processes (gelation of pH-sensitive monomers and emulsion-vesicle transformation). By employing the coupling strategy of antagonistic enzymatic reactions, we engineered a single pH pulse in cell-sized microcompartments, which could contribute to developing synthetic cells with multiple functions.