Research compound reference

Glutathione

Glutathione is a tripeptide of glutamic acid, cysteine and glycine in which glutamic acid is linked through its side-chain carboxyl group. The material is a white to off-white lyophilized powder of 99% or greater purity by HPLC, with a lot-specific Certificate of Analysis, for in vitro laboratory research. This page is a technical reference to the material's identity, chemistry, analytical testing and laboratory handling.

For research use only. Not for human or veterinary, diagnostic or therapeutic use.

The peptide, residue by residue

Three amino acids (L-glutamic acid, L-cysteine and glycine), read from the free amino end of glutamic acid to the free carboxylic acid end of glycine.¹

1EγGlu

2CCys

3GGly

H₂N (N-terminus)COOH (C-terminus)

H-γGlu-Cys-Gly-OH

Residues (the γ-linked glutamic acid keeps a free α-carboxyl group)

The bond between glutamic acid and cysteine uses the side-chain (gamma) carboxyl of glutamic acid, not the alpha carboxyl.

What is glutathione?

Glutathione is a tripeptide of glutamic acid, cysteine and glycine in which glutamic acid is linked through its side-chain carboxyl group. It is catalogued under CAS 70-18-8 and PubChem CID 124886, with the molecular formula C₁₀H₁₇N₃O₆S and a molecular weight of 307.33 g/mol.¹

The material described on this page is intended as a laboratory reagent.

3residues

307.33g/mol¹

≥99%purity by HPLC, per lot

Composition

The peptide has three residues: glutamic acid, cysteine and glycine. Counting the free amino group and the two free carboxylic acid groups, the peptide carries a calculated net charge of about minus one at pH 7.

The sequence contains cysteine, which general peptide guidance identifies as prone to air oxidation.² This is one reason the material is stored dry and sealed.

The gamma linkage

The first peptide bond joins the side-chain (gamma) carboxyl group of glutamic acid to cysteine, rather than the usual alpha carboxyl. PubChem's systematic name records this as a 5-oxopentanoic acid linkage.¹ The free thiol group on cysteine is the site most sensitive to air oxidation.²

Handling

Glutathione is a dry solid as received in the laboratory. General handling guidance for lyophilized peptides applies.²

Allow the sealed container to reach room temperature before opening, so moisture does not condense on the solid.²
Keep the solid dry and away from bright light. Moisture lowers long-term stability.²
Avoid repeated freezing and thawing.²

Storage and stability

State	Temperature	Notes
Dry, sealed	-20 °C, or preferably -80 °C²	Keep dry and away from bright light. Moisture lowers long-term stability.²
Freezing and thawing	Avoid repeated freezing and thawing	Applies to the dry solid.²

How each lot is tested

Each lot in the My Oasis Labs catalogue is tested by an independent third-party laboratory.³ The glutathione certificate page names the testing laboratories and lists each lot's purity, net content and test date. Three measurements are reported.

Identity

Mass spectrometry

Checks that the measured molecular mass matches glutathione. The calculated monoisotopic mass is 307.08 Da.¹

A matching mass is consistent with the expected composition. It does not confirm the order of residues.

Purity

High-performance liquid chromatography (HPLC)

Separates the material from synthesis-related impurities. Purity is reported as the main peak's share of the total detected signal.

Reported per lot. The Oasis Labs specification is 99% or greater.

Quantity

Net content

Measures the mass of material actually present in the sample tested.

Reported per lot on the Certificate of Analysis.

Technical notes

What does the Certificate of Analysis confirm?

Identity by mass spectrometry, purity by HPLC, and the net content of the sample. Mass spectrometry confirms molecular mass, not the order of residues.

Why do molecular weights for glutathione differ slightly between sources?

The figure of 307.33 g/mol is for the form described in the cited PubChem record. Salt forms carry extra counter-ion mass and are often registered separately.

Why is the material freeze-dried?

Peptides are most stable as dry solids. Moisture reduces long-term stability, so the material is lyophilized and kept sealed until use in the laboratory.

Glutathione lot certificates

Each listed glutathione lot has its own certificate covering identity, purity and net content.

View Glutathione certificates Testing methodology

Catalogue entry: Glutathione

References

National Center for Biotechnology Information. PubChem Compound Summary for CID 124886 (Glutathione). pubchem.ncbi.nlm.nih.gov/compound/124886. Accessed 20 October 2026.
MilliporeSigma (Merck KGaA). Handling and storage guidelines for peptides and proteins (technical article). merckmillipore.com. Accessed 14 October 2026.
Oasis Labs. Glutathione Certificate of Analysis page, lot data and testing laboratories (certificate page), and testing methodology, myoasislabs.com/coa-process/.

References document the chemical identity, analytical characterisation and handling of this material. Molecular composition and the calculated net charge are derived from the published sequence.