Enzymatic synthesis and biochemical reactions of fluorinated analogues of L-tyrosine and L-dopa

Abstract

2-Fluoro-L-tyrosine and 3-fluoro-L-tyrosine have been prepared from 3-fluorophenol and 2-fluorophenol, respectively, pyruvate and ammonia using tyrosine phenol-lyase from Citrobacter freundii. Evidence was obtained that 6-fluoro-L-dopa can be made from 4-fluorocatechol by this method. Both fluorotyrosines are substrates for mushroom tyrosinase. Oxygenation of 2-fluoro-L-tyrosine results in 6-fluoro-L-dopa, while 3-fluoro-L-tyrosine gives 5-fluoro-L-dopa. Both fluorotyrosines produce fluoride ion in reactions with tyrosinase, as measured by a fluoride-specific electrode. However, ascorbic acid can suppress fluoride release from 3-fluoro-L-tyrosine, but not from 2-fluoro-L-tyrosine.