Tritium NMR studies of the human carbonic anhydrase I-benzenesulfonamide complex.

Tritium NMR spectroscopy has been used to examine the complex formed by [4-3H]benzenesulfon-amide and human carbonic anhydrase I. The results show that in solution the inhibitor forms a 1:1 complex with the enzyme. A 100-spin computational model of the system, constructed with reference to crystallographic results, was used to interpret tritium relaxation behavior and 3H{1H} NOEs. The analysis shows that the rate of dissociation of the enzyme-sulfonamide complex is 0.35 s-1 and that the aromatic ring of the inhibitor undergoes rapid rotation while complexed.