Rat anti-NO-L-Methionine polyclonal antibody for ELISA, IHC, ICC, WB. Methionine is an essential amino acid, it cannot be synthesized in humans. However, in plants and microorganisms, methionine is synthesized from aspartic acid and cysteine. Methionine plays a role in cysteine, carnitine and taurine synthesis by the transsulfuration pathway, lecithin production, the synthesis of phosphatidylcholine and other phospholipids. Improper conversion of methionine can lead to atherosclerosis. Methionine is a chelating agent.