Inhibition of chicken erythrocyte AMP deaminase by tetraiodofluorescein compounds.

A kinetic study has been performed on the inhibition of the chicken erythrocyte AMP deaminase (AMP aminohydrolase, EC 3.5.4.6) reaction by tetraiodofluorescein and Rose Bengal. These dyes inhibited the enzyme by decreasing its affinity for the substrate without affecting the maximum velocity. Kinetic analysis has shown the inhibition constants for tetraiodofluorescein and Rose Bengal to be 350 and 55 micrometer, respectively, and the presence of 4 binding sites of the enzyme for the inhibitors per enzyme molecule. These results suggest that the fluorescein dyes mimic the AMP binding at the catalytic center of the enzyme, which can be formed by the "dinucleotide fold".