L-Cysteine ke e 'ngoe ea li-amino acid tse 20, ntle le methionine, ke eona feela e nang le sebabole.Ke amino acid e nang le thiol e seng ea bohlokoa e entsoeng ka oxid ho theha Cystine.Ke amino acid e sa hlokahaleng e nang le sebabole ho batho, e amanang le cystine, Cysteine e bohlokoa bakeng sa motsoako oa liprotheine, detoxification, le mesebetsi e fapaneng ea metabolism.E fumanoa ho beta-keratin, protheine e kholo ea manala, letlalo le moriri, Cysteine e bohlokoa tlhahisong ea collagen, hammoho le ho phutholoha ha letlalo le sebopeho.