Glycylmethionine

Glycyl-methionine or Gly-Met is a dipeptide consisting of the amino acids glycine and methionine. It plays a role as a metabolite. It is reverse of Methionylglycine or Met-Gly sequence.

Glycylmethionine

Names
IUPAC name L-Glycyl-L-methionine
Other names (2S)-2-[(2-aminoacetyl)amino]-4-methylsulfanylbutanoic acid
Identifiers
CAS Number	554-94-9 Y
3D model (JSmol)	Interactive image
Abbreviations	gly-met
ChEBI	CHEBI:74120 zwitterion: CHEBI:74393
ChEMBL	ChEMBL330552 Y
ChemSpider	133336 Y
ECHA InfoCard	100.008.252
EC Number	209-076-1
PubChem CID	151282
UNII	0H4L5K3198
InChI Key: PFMUCCYYAAFKTH-YFKPBYRVSA-N Y
SMILES CSCCC(C(=O)O)NC(=O)CN
Properties
Chemical formula	C7H14N2O3S
Molar mass	206.26 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Oxidation

The oxidation of Gly-Met and its reverse sequence, Met-Gly, has differences. Both photooxidation and collision-induced dissociation of Gly-Met happen through electron transfer from either the sulfur atom or the terminal amino group when it is in its uncharged state. This process leads to the formation of α-protons and sulfur-centered cation radicals in Gly-Met.

However, the photooxidation of Met-Gly behaves differently from Gly-Met. The peptide’s conformation plays a crucial role in understanding the oxidation mechanism. In Met-Gly, the process leads to the formation of an open-chain sulfur-centered cation radical. This radical then releases a proton from the N-terminal amino group, resulting in a five-membered cyclic radical structure with a three-electron bond between the sulfur and nitrogen atoms.

Peptides can adopt different conformations—cationic, zwitterionic, or anionic—depending on the solvent and pH. The zwitterionic form of Gly-Met is particularly important as it is responsible for the formation of sulfur-centered radicals. This same mechanism can cause similar damage in proteins.