Isolation and characterisation of 5'-fluorodeoxyadenosine synthase, a fluorination enzyme from Streptomyces cattleya

5′‐Fluorodeoxyadenosine synthase, a C–F bond‐forming enzyme, has been purified from Streptomyces cattleya. The enzyme mediates a reaction between inorganic fluoride and S‐adenosyl‐L‐methionine (SAM) to generate 5′‐fluoro‐5′‐deoxyadenosine. The molecular weight of the monomeric protein is shown to be 32.2 kDa by electrospray mass spectrometry. The kinetic parameters for SAM (K m 0.42 mM, V max 1.28 U/mg) and fluoride ion (K m 8.56 mM, V max 1.59 U/mg) have been evaluated. Both S‐adenosyl‐L‐homocysteine (SAH) and sinefungin were explored as inhibitors of the enzyme. SAH emerged as a potent competitive inhibitor (K i 29 μM) whereas sinefungin was only weakly inhibitory.