Enzymes with identical sequences of amino acids can display different levels of activity when they are encoded with different messenger RNA (mRNA) sequences; however, the reason for this has not been clear. Now, a team led by Edward P. O’Brien has shown that synonymous mutations in mRNA can alter the partitioning of proteins into long-lived soluble misfolded states, and that these different states can possess different levels of activity. The cover depicts an enzyme adopting a misfolded structure during the folding process.

See Jiang et al.

Interlocked nanocarbons have been attracting attention on account of both their intriguing structures and potential utility, but their synthesis is challenging. Now, a team led by Ramesh Jasti has used an active-template approach to efficiently prepare such threaded compounds. A metal ion held in the central cavity of a macrocyclic precursor catalyses cross-coupling reactions to form a series of mechanically interlocked intermediates. These are then converted into fully π-conjugated species, such as the catenanes and rotaxane depicted on the cover.

See May et al.

Stereochemistry is a crucial yet hard to control parameter that influences the physical properties of polymers. Now, Quentin Michaudel and co-workers disclose a stereocontrolled acyclic diene metathesis (ADMET) polymerization that leverages the high stereoselectivity of a dithiolate Ru catalyst and uses specifically designed diene monomers to afford polymers with predictable compositions of cis and trans alkenes. This strategy enables the thermal properties and crystallinity of various polymers to be modulated through modification of their cis:trans alkene content. The cover shows an artistic representation of diene monomers and oligomers undergoing stereocontrolled ADMET through reaction with the Ru catalyst to form cis alkenes.

See Hsu et al.