Periodic Reporting for period 1 - ASSEMZYME (Continuous self-assembly using enzyme mediated supramolecular switching)
Reporting period: 2015-03-24 to 2017-03-23
The aim of this project has been to realise non-equilibrium self-assembled steady states (NESS) of a supramolecular polymer, controlled by competitive enzymatic phosphorylation/dephosphorylation of the building blocks, in which the supramolecular assemblies are pushed and kept out of equilibrium by continuous influx of the chemical fuel ATP, and removal of waste through a membrane reactor.
Maintaining NESS conditions of a self-assembled system is a crucial advancement in the field of supramolecular chemistry, which will open the door to truly functional “living” systems.
At the end of the action, the proposed objectives were fully achieved, and we could successfully demonstrate that it is possible to keep supramolecular polymers in different NESS depending on the influx of chemical fuel supplied, and outflux of waste under continuous flow conditions.
We then worked out the experimental conditions at which both enzymes can work concurrently, and at commensurate speeds. The latter allowed us to obtain transient changes in the supramolecular structure of the polymer when adding ATP to a batch reactor containing the building blocks, and the two enzymes, in analogy with transient self-assembly, that is state-of-the-art in supramolecular chemistry. We could refuel our system, but waste products lead to phosphatase inhibition causing the reaction cycles to stop. The poisoning effect could be overcome by working in an open system under continuous flow conditions (see below). To shed light on the complex dynamics of the enzyme network, we developed a mathematical model based on mass action kinetics and performed numerical simulations.
Finally, we fabricated a membrane reactor, where different sustained NESS could be maintained depending on the level of fuel supplied and waste removed under continuous flow conditions. The result is that the assembly/disassembly process could be kept continuously working for days as long as the fuel is supplied.
These results, going beyond the state-of-the-art in the field, accomplish the objectives of the proposal, and have been reported in the paper “Non-equilibrium steady-states in supramolecular polymerization”, just accepted in NCOMM. In addition, they have been presented, so far, to four international conferences as poster and/or oral presentations (including Burgenstock and Gordon meetings).
In our case, the influx of ATP is the control parameter, which determines the nature of the steady-state, and the distance from the thermodynamic equilibrium. Exploring different steady-states depending on how hard the system is driven, can provide unique insight into the dynamics and structures of artificial self-assemblies far from equilibrium. In general, if supramolecular systems can be driven in this way, it could give rise to sustained supramolecular oscillations analogously to microtubules. To sum up, our work opens an avenue towards the development of more life-like self-assembled materials that can show true adaptability and eventually perform functions as complex as in living systems.