Glutathione structure: GSH vs GSSG

01 / Comparison

Reduced and oxidized glutathione, side by side.

Glutathione is recorded in two forms. Reduced glutathione (GSH) is the tripeptide γ-Glu–Cys–Gly, with a free thiol on its cysteine. Oxidized glutathione (GSSG) is two of those units joined by a disulfide between their cysteines, so its formula is two GSH units less two hydrogens. A label or a measurement should say which form it means.

Reduced and oxidized glutathione
	Reduced (GSH)	Oxidized (GSSG)
Composition	γ-Glu–Cys–Gly	Two γ-Glu–Cys–Gly units
Cysteine sulfur	Free thiol	Disulfide between the two units
Formula	C₁₀H₁₇N₃O₆S	C₂₀H₃₂N₆O₁₂S₂
Molecular weight	307.33 g/mol	612.6 g/mol
CAS number	70-18-8	27025-41-8
PubChem CID	124886	65359

Reference values from public records, not a Pioneer lot specification.

References: [1][2][3][4]

02 / Molecular architecture

A closer look at the chain.

Its three units are glutamate, cysteine and glycine. The first bond uses glutamate’s gamma-carboxyl group. Cysteine contributes the sulfur-containing thiol involved in its redox chemistry.

Pioneer / Reference notesMolecular features

3 amino acids
Gamma-glutamyl linkage
Cysteine thiol

γ-Glu
Cys
Gly

Reduced glutathione reference. The gamma linkage is distinct from a conventional alpha-peptide bond.

Reference information: [1][2][3][4]. Actual lot identity must be verified separately.

An unusual first peptide bond.

Glutathione begins with a gamma-glutamyl linkage. The connection uses glutamate’s side-chain carboxyl group rather than the alpha-carboxyl group used in a conventional peptide backbone. Writing only Glu–Cys–Gly without that qualifier leaves out a distinguishing feature of its chemical connectivity.

Following the sulfur chemistry.

Reduced glutathione, GSH, contains the cysteine thiol. Oxidized glutathione, GSSG, contains a disulfide joining two glutathione units. A measurement of one form and a measurement combining forms answer different questions. The redox form is therefore part of the analyte definition, alongside the underlying amino-acid composition.

Structure and research references: [1][2]

03 / Read the evidence

Research & analytical context.

GSH is an electron donor in glutathione-peroxidase reactions and a co-substrate in glutathione-transferase reactions. Those biochemical roles explain its use in redox and enzyme assays.

Read the references: [1][2][3][4].

The distinction that matters

Reduced GSH and oxidized GSSG are different chemical forms. Confirm which form is supplied and measured rather than treating every glutathione label or assay result as equivalent.

04 / From reference to record

Know the lot, too.

A publication describes its own test material. Your lot’s certificate describes what was tested on that lot. Keep the compound name, batch number and reported methods together when reviewing a result.

Identity & composition

Check sequence or chemical form, terminal modifications, counterion and—where relevant—each blend component.

Analytical results

Read purity, content, sterility and endotoxin results as separate measurements. Only call a test passed when the actual report supports it.

Handling & storage notes

Lyophilized material: Store at −20°C; protect from light and moisture.

Follow the material-specific label and supporting storage documentation. These temperatures do not establish a shelf life.

How to store lyophilized peptides

View Glutathione sizes View the COA library

05 / Reference questions

A few details, explained.

Does GSSG mean the same thing as GSH?

No. They describe distinct redox forms. Reporting an assay as glutathione without explaining which form is measured can make comparisons unclear.

Why is the gamma symbol shown in the chain?

It identifies the unusual glutamate linkage. The symbol is not another residue; it specifies which part of glutamate connects to cysteine.

Read alongside the references: [1][2]

06 / Continue reading

Go to the source.

Each source is labeled by its type. External sources are not Pioneer batch certificates.