Alice Y. Romans, Mary E. Graichen, C.H. Lochmuller, Robert W. Henkens
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引用次数: 18
Abstract
The kinetics of dissociation of Zn2+ from the metalloenzyme carbonic anhydrase was measured over a range of pH, temperature, and acetate concentration. The rate of dissociation is extremely slow at neutral pH (tl/2 ≈ 3 years, 4°C), but increases in almost direct proportion to the hydrogen ion concentration and is enhanced in the presence of 1,10-phenanthroline or acetate. The thermodynamic stability of the zinc-apoenzyme complex was determined over a range of pH from rate data on binding and dissociation (stability constants 109–1011 M−1, 25°C). The great stability of the complex and slow exchange of the apoenzyme ligand is attributed, at least in part, to the rigidity of the multidentate protein ligand.
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