Robuta

https://www.ncbi.nlm.nih.gov/Structure/pdb/3ZVT 3ZVT: Unexpected tricovalent binding mode of boronic acids within the active site of a penicillin... D-ALANYL-D-ALANINE CARBOXYPEPTIDASE2,6 DIMETHOXYBENZAMIDOBORONIC ACIDMAGNESIUM IONSULFATE ION