Glutamine
Glutamine — The most abundant free amino acid in circulation (Gln, Q). Susceptible to deamidation, making it a stability-critical residue in peptide formulations.
What Is Glutamine?
Glutamine (Gln, Q) is a polar amino acid with a carboxamide side chain one carbon longer than asparagine (MW: 146.15 Da). It undergoes deamidation to glutamic acid but at a rate 10-100 times slower than Asn, making it a more stable alternative when amide side-chain functionality is needed.
Roles in Peptide Research
- Stability advantage: Substituting Gln for Asn at deamidation-prone positions improves peptide shelf life
- Pyroglutamate: N-terminal Gln spontaneously cyclizes to pyroglutamate (pGlu), a common modification in bioactive peptides including neurotensin and TRH
- Transglutaminase substrate: Gln is crosslinked to Lys by transglutaminase, used in peptide-protein conjugation
Frequently Asked Questions
What is Glutamine?
The most abundant free amino acid in circulation (Gln, Q). Susceptible to deamidation, making it a stability-critical residue in peptide formulations.
Why is Glutamine important in peptide research?
Glutamine 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.