The first enzymatic method for C–¹⁸F bond formation: the synthesis of 5′‐[¹⁸F]‐fluoro‐5′‐deoxyadenosine for imaging with PET

The use of the key enzyme involved in carbon–fluorine bond formation in Streptomyces cattleya catalysing the formation of 5′‐fluoro‐5′‐deoxyadenosine (5′‐FDA) from fluoride ion and S ‐adenosyl‐l‐methionine (SAM) was explored for its potential application in fluorine‐18 labelling of the adenosine derivative. Enzymatic radiolabelling of [ 18 F]‐5′‐FDA was successfully carried out starting from SAM and [ 18 F]HF when the concentration of the enzyme preparation was increased from sub‐mg/ml values to mg/ml values. The purity of the enzyme had no measurable effect on the radiochemical yield of the reaction and the radiochemical purity of [ 18 F]‐5′‐FDA.