Glutathione

Route: Glutamate + Cysteine → γ-Glutamylcysteine + Glycine → Glutathione

Glutathione is the tripeptide γ-glutamyl-cysteinyl-glycine. The first enzyme, glutamate-cysteine ligase, joins the side-chain carboxyl group of glutamate to the amino group of cysteine, which is why the peptide bond is called gamma. Glutathione synthetase then adds glycine to the carboxyl end of cysteine. Each step costs one ATP. In humans the first step limits the rate and is slowed by glutathione itself. The thiol group of cysteine carries the chemistry: two glutathione molecules can join through a disulfide bond, which lets the cell use glutathione to pass electrons to other molecules.

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Steps

Enzyme names and EC numbers are those used on the interactive board. Checked against sources: see the claim table in the repository (tools/pathway_data/checks).