30089 Sigma-Aldrich


BioUltra, ≥98.5% (RT)

Synonym: (R)-2-Amino-3-mercaptopropionic acid

  • CAS Number 52-90-4

  • Linear Formula HSCH2CH(NH2)CO2H

  • Molecular Weight 121.16

  •  Beilstein/REAXYS Number 1721408

  •  EC Number 200-158-2

  •  MDL number MFCD00064306

  •  eCl@ss 32160406

  •  PubChem Substance ID 57648406



Related Categories Amino Acids, Amino acids, BioUltra, Biochemicals and Reagents, Cell Biology,
product line   BioUltra
assay   ≥98.5% (RT)
optical activity   [α]20/D +8.0±0.5°, c = 5% in 5 M HCl
impurities   insoluble matter, passes filter test
  ≤0.5% foreign amino acids
ign. residue   ≤0.05% (as SO4)
loss   ≤0.05% loss on drying, 20 °C (HV)
mp   240 °C (dec.) (lit.)
solubility   1 M HCl: 1 M at 20 °C, clear, colorless
anion traces   chloride (Cl-): ≤100 mg/kg
  sulfate (SO42-): ≤50 mg/kg
cation traces   Al: ≤5 mg/kg
  As: ≤0.1 mg/kg
  Ba: ≤5 mg/kg
  Bi: ≤5 mg/kg
  Ca: ≤10 mg/kg
  Cd: ≤5 mg/kg
  Co: ≤5 mg/kg
  Cr: ≤5 mg/kg
  Cu: ≤5 mg/kg
  Fe: ≤5 mg/kg
  K: ≤50 mg/kg
  Li: ≤5 mg/kg
  Mg: ≤5 mg/kg
  Mn: ≤5 mg/kg
  Mo: ≤5 mg/kg
  NH4+: ≤500 mg/kg
  Na: ≤100 mg/kg
  Ni: ≤5 mg/kg
  Pb: ≤5 mg/kg
  Sr: ≤5 mg/kg
  Zn: ≤5 mg/kg
λ   1 M in 1 M HCl
UV absorption   λ: 260 nm Amax: 1.5
  λ: 280 nm Amax: 0.2



L-Cysteine has been used in quenching of unreacted maleimide during antibody grafting. It has also been used in the preparation of nitrosocysteine stock solution, that has been employed to induce S-nitrosylation to achieve reversible cysteine modification.

Biochem/physiol Actions

Cysteine is one of the functional amino acids that regulates metabolism for growth, reproduction, maintenance and immunity. Cysteine provides the disulfide linkage in proteins. It is directly associated with the transport of sulfur. Taurine, a metabolic product of cysteine acts as an antioxidant and controls the cellular redox state. Cysteine is involved in the formation of hydrogen sulfide that is utilized as a signaling molecule.

NMDA glutamatergic receptor agonist.

Safety & Documentation

Safety Information

Personal Protective Equipment 
NONH for all modes of transport
WGK Germany 


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Milli-Q® Water Purification Solutions
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