Cysteine as a Monothiol Reducing Agent to Prevent Copper-Mediated Oxidation of Interferon Beta During PEGylation by CuAAC

Potentiating Tweezer Affinity to a Protein Interface with Sequence-Defined Macromolecules on Nanoparticles

Survivin, a well-known member of the inhibitor of apoptosis protein family, is upregulated in many cancer cells, which is associated with resistance to chemotherapy. To circumvent this, inhibitors are currently being developed to interfere with the nuclear export of survivin by targeting its protein-protein interaction (PPI) with the export receptor CRM1. Here, we combine for the first time a supramolecular tweezer motif, sequence-defined macromolecular scaffolds, and ultrasmall Au nanoparticles (us-AuNPs) to tailor a high avidity inhibitor targeting the survivin-CRM1 interaction. A series of biophysical and biochemical experiments, including surface plasmon resonance measurements and their multivalent evaluation by EVILFIT, reveal that for divalent macromolecular constructs with increasing linker distance, the longest linkers show superior affinity, slower dissociation, as well as more efficient PPI inhibition. As a drawback, these macromolecular tweezer conjugates do not enter cells, a critical feature for potential applications. The problem is solved by immobilizing the tweezer conjugates onto us-AuNPs, which enables efficient transport into HeLa cells. On the nanoparticles, the tweezer valency rises from 2 to 16 and produces a 100-fold avidity increase. The hierarchical combination of different scaffolds and controlled multivalent presentation of supramolecular binders was the key to the development of highly efficient survivin-CRM1 competitors. This concept may also be useful for other PPIs.

Expanding the versatility and scope of the oxime ligation: rapid bioconjugation to disulfide-rich peptides

The oxime ligation is a valuable bioorthogonal conjugation reaction but with limited compatibility with disulfide-rich peptides/proteins and time-sensitive applications. Here we overcome these limitations by introducing a strategy that supports regiospecific control, oxidative folding, production of stable aminooxy-precursors for on-demand modification, and complete ligation within 5 min.

Future prospects for noncanonical amino acids in biological therapeutics

There is growing evidence that noncanonical amino acids (ncAAs) can be utilized in the creation of biological therapeutics ranging from protein conjugates to cell-based therapies. However, when does genetically encoding ncAAs yield biologics with unique properties compared to other approaches? In this review, we attempt to answer this question in the broader context of therapeutic development, emphasizing advances within the past two years. In several areas, ncAAs add valuable routes to therapeutically relevant entities, but application-specific needs ultimately determine whether ncAA-mediated or alternative solutions are preferred. Looking forward, using ncAAs to perform 'protein medicinal chemistry,' in which atomic-level changes to proteins dramatically enhance therapeutic properties, is a promising emerging area. Further upgrades to the performance of ncAA incorporation technologies will be essential to realizing the full potential of ncAAs in biological therapeutics.

Rapid and highly sensitive detection of extracellular and intracellular H2S by an azide-functionalized Al(iii)-based metal–organic framework

Fast and highly sensitive sensing of both extracellular and intracellular H₂S by an Al(iii)-based CAU-10-N₃MOF is presented.

Measuring and Suppressing the Oxidative Damage to DNA During Cu(I)-Catalyzed Azide-Alkyne Cycloaddition

We have used the quantitative polymerase chain reaction (qPCR) to measure the extent of oxidative DNA damage under varying reaction conditions used for copper(I)-catalyzed click chemistry. We systematically studied how the damage depends on a number of key reaction parameters, including the amounts of copper, ascorbate, and ligand used, and found that the damage is significant under nearly all conditions tested, including those commonly used for bioconjugation. Furthermore, we discovered that the addition of dimethyl sulfoxide, a known radical scavenger, into the aqueous mixture dramatically suppresses DNA damage during the reaction. We also measured the efficiency of cross-linking two short synthetic oligonucleotides via click chemistry, and found that the reaction could proceed reasonably efficiently even with DMSO present. This approach for screening both DNA damage and reactivity under a range of reaction conditions will be valuable for improving the biocompatibility of click chemistry, and should help to extend this powerful synthetic tool for both in vitro and in vivo applications.