I-L-Cysteine ingenye yama-amino acid emvelo angama-20 futhi, ngaphandle kwe-methionine, iyona kuphela equkethe isulfure.Kuyi-amino acid engabalulekile equkethe i-thiol ekhishwa nge-oxid ukuze yakhe i-Cystine.Kuyi-amino acid engabalulekile enesulfure kubantu, ehlobene ne-cystine, i-Cysteine ibalulekile ekuhlanganiseni kwamaprotheni, ukukhipha ubuthi, kanye nemisebenzi ehlukahlukene ye-metabolic.Itholakala ku-beta-keratin, iphrotheni eyinhloko ezinzipho, esikhunjeni nasezinweleni, i-Cysteine ibalulekile ekukhiqizeni i-collagen, kanye nokunwebeka kwesikhumba nokuthungwa.