Sorry for the probably dumb question, I am a complete chemistry noob. Can the experts explain to me how one would replace the carboxyl group with a methyl group? Could yeast be genetically engineered to perform the synthesis? I know there are certain enzymes like N-alpha methyltransferases that might be able to achieve this, but its probably BS. Otherwise someone else would have already done this , right? I mean our body itself transforms L-Phenylalanine -> L-Tyrosin -> L-DOPA -> Dopamine, correct?
Regards