Pnictogen‐Bonding Enzymes.

The objective of this study was to create artificial enzymes that capitalize on pnictogen bonding, a σ‐hole interaction that is essentially absent in biocatalysis. For this purpose, stibine catalysts were equipped with a biotin derivative and combined with streptavidin mutants to identify an efficient transfer hydrogenation catalyst for the reduction of a fluorogenic quinoline substrate. Increased catalytic activity from wild‐type streptavidin to the best mutants coincides with the depth of the σ hole on the Sb(V) center, and the emergence of saturation kinetic behavior. Michaelis–Menten analysis reveals transition‐state recognition in the low micromolar range, more than three orders of magnitude stronger than the millimolar substrate recognition. Carboxylates preferred by the best mutants contribute to transition‐state recognition by hydrogen‐bonded ion pairing and anion‐π interactions with the emerging pyridinium product. The emergence of challenging stereoselectivity in aqueous systems further emphasizes compatibility of pnictogen bonding with higher order systems catalysis. [ABSTRACT FROM AUTHOR]