Ligand Binding Properties of Bovine Liver Adenosine Kinase

Abstract

Bovine liver adenosine kinase displays a characteristic intrinsic fluorescence due to 3 tryptophans/mol. This fluorescence is very sensitive to ligand binding and was used to characterize the ligand binding sites of the enzyme. ADP or ATP showed a monophasic saturation curve consistent with the existence of one binding site. In contrast, adenosine and AMP gave biphasic saturation curves suggesting the existence of at least two binding sites with high and low affinity. These binding sites were further characterized by studying the complexation of adenosine kinase with O-(N-methylanthraniloyl)adenosine nucleoside or nucleotide analogues.