Methionine
Methionine — An essential sulfur-containing amino acid (Met, M) that serves as the initiator of protein synthesis and is susceptible to oxidation in peptide formulations.
What Is Methionine?
Methionine (Met, M) is a sulfur-containing essential amino acid with a thioether side chain (-CH2CH2SCH3), molecular weight 149.21 Da. It is the universal translation initiator (start codon AUG) and the most oxidation-sensitive residue in peptides, making it a critical consideration for peptide stability and storage.
Methionine Oxidation
Methionine oxidizes to methionine sulfoxide (Met(O), +16 Da) through reaction with air, peroxides, or metal-catalyzed reactive oxygen species. This is the most common chemical degradation pathway during peptide storage. Methionine sulfoxide can be further oxidized to methionine sulfone (+32 Da), which is irreversible.
Prevention and Detection
- Storage: Lyophilize under nitrogen or argon. Store at -20°C with desiccant
- Formulation: Add free methionine (0.1-1 mM) as a sacrificial antioxidant in liquid formulations
- Detection: +16 Da shift on MS. Earlier elution on reversed-phase HPLC
Frequently Asked Questions
What is Methionine?
An essential sulfur-containing amino acid (Met, M) that serves as the initiator of protein synthesis and is susceptible to oxidation in peptide formulations.
Why is Methionine important in peptide research?
Methionine is a fundamental concept in amino acid as it relates to peptide science. It directly influences experimental design, compound characterization, and the reliability of research outcomes across biochemistry and molecular biology disciplines.