An Elusive Task: A Clinically Useful Inhibitor of Metallo-β-Lactamases.- Inhibitors of Histidinol Dehydrogenase.- Botulinum Neurotoxin, Tetanus Toxin, and Anthrax Lethal Factor Countermeasures.- Inhibition and Activity Regulation of Bacterial Collagenases.- Fungal Carbonic Anhydrases and Their Inhibition.- Protozoan Carbonic Anhydrases.- Bacterial Carbonic Anhydrases.