FMet

N-Formylmethionine
Names

IUPAC name (S)-2-Formylamino-4-methylsulfanylbutanoic acid
Other names 2-Formylamino-4-methylsulfanyl-butyric acid; Formylmethionine; N-Formyl(methyl)homocysteine
Identifiers
CAS Number	4289-98-9^Y
3D model (Jmol)	Interactive image
Abbreviations	fMet
EC Number	224-322-8
PubChem	911
SMILES CSCCC(NC=O)C(O)=O
Properties
Chemical formula	C₆H₁₁NO₃S
Molar mass	177.22 g/mol
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (ε_r), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y (what is ^YN ?)
Infobox references

N-Formylmethionine (fMet) is a derivative of the amino acid methionine in which a formyl group has been added to the amino group. It is specifically used for initiation of protein synthesis from bacterial and organellar genes, and may be removed post-translationally.

fMet plays a crucial part in the protein synthesis of bacteria, and chloroplasts. It is not used in cytosolic protein synthesis of eukaryotes, where eukaryotic nuclear genes are translated. It is also not used by Archaea. In the human body, fMet is recognized by the immune system as foreign material, or as an alarm signal released by damaged cells, and stimulates the body to fight against potential infection.

fMet is a starting residue in the synthesis of proteins in bacteria, and, consequently, is located at the N-terminus of the growing polypeptide. fMet is delivered to the ribosome (30S) - mRNA complex by a specialized tRNA (tRNA^fMet) which has a 3'-UAC-5' anticodon that is capable of binding with the 5'-AUG-3' start codon located on the mRNA. fMet is thus coded by the same codon as methionine; however, AUG is also the translation initiation codon. When the codon is used for initiation, fMet is used instead of methionine, thereby forming the first amino acid as the peptide chain is synthesized. When the same codon appears later in the mRNA, normal methionine is used. Many organisms use variations of this basic mechanism.

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