In E. coli ( prokaryote ) leaving just the N - terminal methionine residue .
E. coli ( prokaryote ) is an enzyme called formylmethionine deformylase can cleave the formyl group .
In E. coli ( prokaryote ) , an enzyme called formylmethionine deformylase can cleave the formyl group , leaving just the N - terminal methionine residue .