Thiol side chain forms disulfide bridges critical to protein tertiary structure (e.g., immunoglobulins, insulin, keratin). Rate-limiting precursor to glutathione (γGlu-Cys-Gly) and taurine. Central to metallothionein's metal-binding. Free cysteine is unstable in aqueous solution — most supplementation uses NAC or cystine (dimer).
Dosing Guidelines
PO: Typical 1 g (Range: 1–1 g)
Target Organ Systems
endocrine
Interactions
NAC (synergistic): NAC is the N-acetyl prodrug; same downstream effects. No need to co-supplement.