Cover Feature: A Tetrahedral Boronic Acid Diester Formed by an Unnatural Amino Acid in the Ligand Pocket of an Engineered Lipocalin (ChemBioChem 4/2020)

The first crystal structure of a specific cyclic diester formed between a solvated boronic acid, located in the ligand pocket of an engineered lipocalin protein, and a cis‐diol compound is reported. Even though the sugar/diol binding activity of boric acid and its derivatives has been known for almost a century, structural information on corresponding complexes has remained scarce up to now. More information can be found in the communication by A. Skerra et al. on page 469 in Issue 4, 2020 (DOI: 10.1002/cbic.201900405).