L-Cysteine S-sulfate (LCSS) is used as an NMDA glutamatergic receptor agonist. It serves as a substrate for cystine lyase(s).
Cysteine is one of the functional amino acids that are associated with growth, reproduction, maintenance and immunity. Cysteine is a source of disulfide linkage in protein and is associated with sulfur transport. At physiological pH, cysteine undergoes rapid oxidation to form cystine. Reduced availability of cysteine or cystine, influences leukocyte metabolism. L-Cysteine serves as a precursor for the rate limiting step in glutathione synthesis that occurs in neurons. It donates inorganic sulfate for detoxification reactions. Therefore, L-cysteine might be associated with neuroprotection. It is found to obstruct the entry of heavy metal ions across the blood-brain barrier into the brain. Increased levels of L-cysteine might lead to neurotoxicity.