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Many natural proteins contain flexible loops utilizing well-defined complementary surface regions of their interacting partners and usually undergo major structural rearrangements to allow perfect binding. The molecular recognition of such flexible structures is still highly challenging due to the inherent conformational dynamics. Notably, protein-protein interactions are on the other hand characterized by a multivalent display of complementary binding partners to enhance molecular affinity and specificity. Imitating this natural concept, we here report the rational design of advanced multivalent supramolecular tweezers that allow addressing two lysine and arginine clusters on a flexible protein surface loop. The protease Taspase 1, which is involved in cancer development, carries a basic bipartite nuclear localization signal (NLS) and thus interacts with Importin α, a prerequisite for proteolytic activation. Newly established synthesis routes enabled us to covalently fuse several tweezer molecules into multivalent NLS ligands. The resulting bi- up to pentavalent constructs were then systematically compared in comprehensive biochemical assays. In this series, the stepwise increase in valency was robustly reflected by the ligands' gradually enhanced potency to disrupt the interaction of Taspase 1 with Importin α, correlated with both higher binding affinity and inhibition of proteolytic activity.

The COVID-19 pandemic caused by SARS-CoV-2 presents a global health emergency. Therapeutic options against SARS-CoV-2 are still very limited but urgently required. Molecular tweezers are supramolecular agents that destabilize the envelope of viruses resulting in a loss of viral infectivity. Here, we show that first-generation tweezers, CLR01 and CLR05, disrupt the SARS-CoV-2 envelope and abrogate viral infectivity. To increase the antiviral activity, a series of 34 advanced molecular tweezers were synthesized by insertion of aliphatic or aromatic ester groups on the phosphate moieties of the parent molecule CLR01. A structure-activity relationship study enabled the identification of tweezers with a markedly enhanced ability to destroy lipid bilayers and to suppress SARS-CoV-2 infection. Selected tweezer derivatives retain activity in airway mucus and inactivate the SARS-CoV-2 wildtype and variants of concern as well as respiratory syncytial, influenza, and measles viruses. Moreover, inhibitory activity of advanced tweezers against respiratory syncytial virus and SARS-CoV-2 was confirmed in mice. Thus, potentiated tweezers are broad-spectrum antiviral agents with great prospects for clinical development to combat highly pathogenic viruses. CA Sanchez-Garcia und CA Schrader und CA extern

Protein recognition by designed protein ligands is highly challenging, but bears great opportunities. Supramolecular chemists have recently been able to synthesize tailored ligands with remarkable protein recognition properties which are absent in the natural binding partners, and which lead to synergistic effects, positive cooperativity and exquisite selectivity. Thus, the combination of powerful charged interactions with hydrophobic forces has recently led to new prototypes of protein surface binders. This review summarizes the development of molecular tweezers (part 1) and clips (part 2) as unique tools for protein recognition. The parts begin with molecular tweezers for basic amino acid inclusion and the discovery of diphosphate clips for efficient cofactor binding, respectively. Gratifyingly, both host molecules complement each other due to their different molecular shapes. Molecular tweezers will be presented first in their interaction with amino acids and small disordered peptides, where they generally complex each Lys and Arg; then the review will proceed to tweezer complexation with protein surfaces, elucidating the preference for well-accessible basic residues and various examples of protein targeting and interference with protein–protein interactions. Finally, we discuss the advantages of additional recognition elements on the tweezer skeleton, which opens the door to numerous advanced applications in chemical biology and drug discovery. For the clips, we describe in detail the inclusion of two important cationic cofactors, followed by applications on cofactor-mediated enzymatic processes.