Molecular glues for manipulating enzymes: trypsin inhibition by benzamidine-conjugated molecular glues† †Electronic supplementary information (ESI) available: Synthesis of TEG–BA, Gluen–BA, mGluen–BA and Gluen–Ph; 1H NMR, 13C NMR, MALDI-TOF MS, electronic absorption, and CD spectra; zeta potential distributions; SLS plots; DLS histograms; and related experimental procedures. See DOI: 10.1039/c5sc00524h Click here for additional data file.

Water-soluble bioadhesive polymers bearing multiple guanidinium ion (Gu) pendants at their side-chain termini (Gluen–BA, n 1⁄4 10 and 29) that were conjugated with benzamidine (BA) as a trypsin inhibitor were developed. The Gluen–BA molecules are supposed to adhere to oxyanionic regions of the trypsin surface, even in buffer, via a multivalent Gu/oxyanion salt-bridge interaction, such that their BA group properly blocks the substrate-binding site. In fact, Glue10–BA and Glue29–BA exhibited 35and 200-fold higher affinities for trypsin, respectively, than a BA derivative without the glue moiety (TEG–BA). Most importantly, Glue10–BA inhibited the protease activity of trypsin 13-fold more than TEG–BA. In sharp contrast, Glue27–BA, which bears 27 Gu + units along the main chain and has a 5-fold higher affinity than TEG–BA for trypsin, was inferior even to TEG–BA for trypsin inhibition.