L-Methionine

L-Methionine (CAS 63-68-3, C5H11NO2S, molecular weight 149.21) is one of the two sulfur-bearing proteinogenic amino acids and one of the nine that the human body cannot synthesise. Its side chain carries a thioether - a sulfur atom capped with a methyl group - and that single structural detail governs both its biochemistry and, as it happens, its tariff classification. The material presents as white flaky crystals or crystalline powder with a characteristic sulfurous note, melting with decomposition around 280-281 °C, soluble in water at roughly 5.7 g per 100 mL at 25 °C and readily soluble in dilute acids and alkalis. It is light-sensitive and ships in light-protected packaging. Methionine is the initiator residue for protein synthesis in eukaryotic cells and the precursor of S-adenosylmethionine, the principal methyl donor in cellular transmethylation. Through the transsulfuration pathway it also supplies the sulfur that becomes cysteine, and downstream, taurine and glutathione. In plant proteins such as soy it is typically the first-limiting amino acid, which is why it appears so consistently in feed formulations and plant-protein fortification. Commercial L-methionine reaches the market by two routes: direct fermentation, operated at scale by CJ CheilJedang, and resolution of synthetic DL-methionine produced from acrolein and methyl mercaptan through the hydantoin (Hain) or cyanohydrin process. Neither route uses animal-derived raw materials, and Thovek states the actual route on the specification sheet for buyers who need it for label copy or supplier audits. Supply covers USP, Ph. Eur., JP and food-grade material, with crystalline and milled cuts to suit direct compression, dry blending or solution work. Each lot ships with a Certificate of Analysis carrying assay, specific rotation, loss on drying, residue on ignition and elemental impurity data, alongside SDS, origin declaration and the India-origin export paperwork for the 29304000 tariff line.