N-formylmethionine

N-Formylmethionine (fMet) is an amino acid that is found in all living cells. It is a derivative of the amino acid methionine, in which a formyl group has been added to methionine's amino group (catalyzed by the enzyme transformylase when Met is attached to tRNA.fMet, but not to tRNA.Met).

N-Formylmethionine plays a crucial role in the protein biosynthesis of bacteria, archaea, mitochondria and chloroplasts. Bacteria utilize N-formylmethionine (f-Met) rather than methionine at the N-terminal of the elongating polypeptide chain.

Compare to methionine.

f-Met amino acid RNA code: AUG tRNA.fMet & tRNA.Met