Biocatalytic production of 7-methylxanthine by a caffeine-degrading Escherichia coli strain.

7-Methylxanthine, a derivative of caffeine (1,3,7-trimethylxanthine), is a high-value compound that has multiple medical applications, particularly with respect to eye health. Here, we demonstrate the biocatalytic production of 7-methylxanthine from caffeine using Escherichia coli strain MBM019, which was constructed for production of paraxanthine (1,7-dimethylxanthine). The mutant N-demethylase NdmA4, which was previously shown to catalyze N -demethylation of caffeine to produce paraxanthine, also retains N -demethylation activity toward paraxanthine.