The attraction of H‐bonding: Proline derivatives with a C4‐endo ring pucker and a preference for the trans amide conformer are introduced as building blocks to tune the cis/trans amide conformer ratio in Xaa‐Pro bonds within peptides. Noncovalent interactions, such as hydrogen bonding between the substituent at C4 of the proline ring and the amide backbone are key for favoring or disfavoring the trans conformer (see picture).

In the presence of human carbonic anhydrase II, aryl-sulfonamide-bearing IrCp* pianostool complexes catalyze the asymmetric transfer hydrogenation of imines. Critical cofactor-protein interactions revealed by the X-ray structure of [(h 5 -Cp*)Ir(pico 4)Cl] 9 3 WT hCA II were genetically optimized to improve the catalytic performance of the artificial metalloenzyme (68% ee, k cat /K M 6.11 Â 10 À3 min À1 mM À1).

d(6)-piano-stool complexes bearing an arylsulfonamide anchor display sub-micromolar affinity towards human Carbonic Anhydrase II (hCA II). The 1.3 Å resolution X-ray crystal structure of [(η(6)-C(6)Me(6))Ru(bispy 3)Cl](+)⊂ hCA II highlights the nature of the host-guest interactions.

Unraveling the native structure of protein–ligand complexes in solution enables rational drug design.

Permanent multipoles (MTPs) embody a natural extension to common point-charge (PC) representations in atomistic simulations. In this work, we propose an alternative to the computationally expensive MTP molecular dynamics simulations by running a simple PC simulation and later reevaluate-"score''-all energies using the more detailed MTP force field. The method, which relies on the assumption that the PC and MTP force fields generate closely related phase spaces, is accomplished by enforcing identical sets of monopoles between the two force fields-effectively highlighting the higher MTP terms as a correction to the PC approximation. We first detail our consistent parametrization of the electrostatics and van der Waals interactions for the two force fields. We then validate the method by comparing the accuracy of protein-ligand binding free energies from both PC and MTP-scored representations with experimentally determined binding constants obtained by us. Specifically, we study the binding of several arylsulfonamide ligands to human carbonic anhydrase II. We find that both representations yield an accuracy of 1 kcal/mol with respect to experiment. Finally, we apply the method to rank the energetic contributions of individual atomic MTP coefficients for molecules solvated in water. All in all, MTP scoring is a computationally appealing method that can provide insight into the multipolar electrostatic interactions of condensed-phase systems.