Scheme 1. Top: Structures of MER and IME with the 6α-Hydroxyethyl Group Is Highlighted in Red; Bottom: Deacylation Mechanism in OXA-48 with a Carbapenem Substrate (Δ2 Tautomer); Starting from the AC, the Antibiotic Is Deacylated via TI Formation (1 → 2), Which Collapses to Yield the Hydrolyzed Antibiotic (3).