Inhibition of fructose-1,6-biphosphatase by the photoaffinity AMP analog, 8-azidoadenosine 5'-monophosphate

Inhibition studies with the photoreactive AMP analog, 8-azidoadenosine 5'-monophosphate (8-azido-AMP), demonstrate that this compound is, like AMP, an allosteric inhibitor of pig kidney and muscle fructose-1,6-biphosphateses. Photolysis of a mixture of purified pig kidney fructose-1,6-biphosphate and 8-azido-[14C]AMP results in the loss of enzyme activity and the reagent is incorporated to the protein. The incorporation of reagent linearly correlates with the loss of enzyme activity. Extrapolation to zero activity correlates with the incorporation of 3.7 mol of reagent/mol of enzyme (i.e. 0.9 per subunit). Thus, 8-azido-AMP appears to be a photoaffinity label for the allosteric AMP binding site of fructose-1,6-biphosphatase.