Fluorine NMR studies of the human carbonic anhydrase-3,5-difluorobenzenesulfonamide complex

Fluorine and nitrogen-15 NMR experiments are described which show that 3,5-difluorobenzenesulfonamide binds to human carbonic anhydrase I in a 1:1 complex, that the bound inhibitor is present as an anion and that the aromatic ring of the inhibitor undergoes rapid rotation in the complex in spite of likely interactions with the aromatic ring of Phe-91 which are strong enough to give an appreciable F-19{H-1} NOE. A previously predicted enhancement of binding by fluorination of the inhibitor was confirmed. (C) 1998 John Wiley & Sons, Ltd.