This figure is a chemical equation showing the ring-opening reaction. The bond in the beta-lactam ring (highlighted in pink) that is broken is the amide linkage between the carbonyl (C=O) carbon and the nitrogen to which it is attached. This N atom is shared between the beta-lactam ring and the adjacent ring. The result of the hydrolysis reaction is a free carboxyl (COOH) group and an NH group in the remaining ring.