Cdc42, a Rho-family GTPase, plays a pivotal role in establishing polarity in Saccharomyces cerevisiae by accumulating on the membrane at the site of bud emergence. Cdc42’s ability to bind to membranes, mediated by prenylation, is essential for its function. Prenylation involves either the post-translational addition of a 15-carbon farnesyl group or a 20-carbon geranylgeranyl group to Cdc42’s C-terminus. One of the major challenges in studying the physical and chemical interactions of Cdc42 at the polarity spot in vitro is obtaining prenylated Cdc42. Here, we present a streamlined, sortase A-based approach to farnesylate Cdc42 in vitro. This method uses Escherichia coli-expressed Cdc42 with a sortase A recognition motif, facilitating efficient farnesylation and purification using a size exclusion-based strategy. The farnesylated Cdc42 retains functionality, as evidenced by membrane binding and by its GEF-regulatory GTPase activity, making it suitable for further biophysical and biochemical investigations.

Dynamic covalent (DCv) ureas are highly diverse chemical moieties and have become one of the most used motifs in self-healing materials and beyond. This review summarizes the historical development, properties, and applications of DCv ureas in different fields of organic chemistry, materials chemistry, and biomedical applications and provides guidance on the design of different DCv ureas depending on stability and dynamicity requirements.

Over the last few decades, the study of more complex, chemical systems closer to those found in nature, and the interactions within those systems, has grown immensely. Despite great efforts, the need for new, versatile, and robust chemistry to apply in CRNs remains. In this Feature Article, we give a brief overview over previous developments in the field of systems chemistry and how β′-substituted Michael acceptors (MAs) can be a great addition to the systems chemist's toolbox. We illustrate their versatility by showcasing a range of examples of applying β′-substituted MAs in CRNs, both as chemical signals and as substrates, to open up the path to many applications ranging from responsive materials, to pathway control in CRNs, drug delivery, analyte detection, and beyond.

Dynamic covalent (DCv) ureas have been used abundantly to design self-healing materials. We demonstrate that apart from self-healing materials, the species present in the equilibrium of DCv ureas can be employed as responsive organocatalysts. Easily controllable stimuli like heat or addition of water shift the equilibrium towards isocyanate and free base which can function as an in situ released reagent. We demonstrate this application of DCv ureas with two examples. Firstly, we use the liberated base to catalytically activate a latent organocatalyst for acylhydrazone formation. Secondly, this base can be employed in an equimolar manner to trigger the release of nitrile-N-oxides from chlorooximes, which react with acrylate-terminated polymers to form an isoxazoline polymer gel.

Shunts, alternative pathways in chemical reaction networks (CRNs), are ubiquitous in nature, enabling adaptability to external and internal stimuli. We introduce a CRN in which the recovery of Michael-accepting species is driven by oxidation chemistry. Using weak oxidants can enable access to two shunts within this CRN with different kinetics and a reduced number of side reactions compared to the main cycle that is driven by strong oxidants. Furthermore, we introduce a strategy to recycle one of the main products under flow conditions to partially reverse the CRN and control product speciation throughout time. These findings introduce new levels of control over artificial CRNs, driven by redox chemistry, narrowing the gap between synthetic and natural systems.