ELIMINATION OF THE 7-TRIFLUOROMETHYL GROUP FROM 6,7-BIS(TRIFLUOROMETHYL)-8-RIBITYLLUMAZINES - STEREOSELECTIVE CATALYSIS BY THE LUMAZINE SYNTHASE OF BACILLUS-SUBTILIS

Both diastereomers of 7-bis(trifluoromethyl)-7-hydroxy-8-ribityllumazi ne decompose in neutral or mild basic aqueous solution by elimination of the 7-CF3 group yielding 6-(trifluoromethyl)-7-oxo-8-ribityllumazin e. It is suggested that the reaction starts with deprotonation of the 7-OH group, followed by release of the CF3 carbanion and formation of a carbonyl oxygen. The reaction was catalyzed diastereoselectively by the lumazine synthase/riboflavin synthase complex from Bacillus subtil is, which resulted from a decrease in the pK(2) of the 7-OH group by t he enzyme.