Fluorinase

The fluorinase enzyme (EC 2.5.1.63, also known as adenosyl-fluoride synthase) catalyzes the reaction between fluoride ion and the co-factor S-adenosyl-L-methionine to generate L-methionine and 5'-fluoro-5'-deoxyadenosine, the first committed product of the fluorometabolite biosynthesis pathway.

[3] A homologous chlorinase enzyme, which catalyses the same reaction with chloride rather than fluoride ion, has been isolated from Salinospora tropica, from the biosynthetic pathway of salinosporamide A.

[4] The fluorinase catalyses an SN2-type nucleophilic substitution at the C-5' position of SAM, while L-methionine acts as a neutral leaving group.

Incubation of SAM and chloride ion with the fluorinase does not result in generation of 5'-chloro-5'-deoxyadenosine (ClDA), unless an additional enzyme, an L-amino acid oxidase, is added.

When [18F]fluoride is used, this transhalogenation reaction can be used for the synthesis of radiotracers for positron emission tomography.

The fluorinase catalyses the reaction between fluoride ion and the co-factor S -adenosyl-L-methioinine (SAM) to generate 5'-fluoro-5'-deoxyadenosine (FDA) and L-methionine (L-Met). [ 1 ]
The fluorinase can also catalyse the reaction between chloride ion and the co-factor S -adenosyl-L-methioinine (SAM) to generate 5'-chloro-5'-deoxyadenosine (ClDA) and L-methionine (L-Met). The reaction only proceeds when L-methionine is removed from the reaction by an L-amino acid oxidase, driving the reaction equilibrium towards ClDA.
Incubation of ClDA with the fluorinase in the presence of L-methionine and fluoride ion results in the generation of FDA, through a SAM intermediate.