In chemistry, the addition of a formyl functional group is
termed formylation. A formyl functional group consists of a
carbonyl bonded to a hydrogen. When attached to an R group, a
formyl group is called an aldehyde. Formylation has been
identified in several critical biological processes. Methionine
was first discovered to be formylated in E. coli by Marcker and
Sanger in 1964 and was later identified to be involved in the
initiation of protein synthesis in bacteria and organelles. The
formation of n-formylmethionine is catalyzed by the enzyme
methionyl-tRNAMet transformylase. Additionally, two formylation
reactions occur in the de novo biosynthesis of purines. These
reactions are catalyzed by the enzymes glycinamide
ribonucleotide (GAR) transformylase and
5-aminoimidazole-4-carboxyamide ribotide (AICAR) transformylase.
More recently, formylation has been discovered to be a histone
modification, which may modulate gene expression. Formylation
reactions in biology  Formylation in protein synthesis  In
bacteri