L-Proline

L-Proline (CAS 147-85-3, C5H9NO2, molecular weight 115.13) is the structural oddity among the proteinogenic amino acids. Its nitrogen is not a free amine but part of a saturated five-membered pyrrolidine ring, which makes proline a secondary amine - an imino acid - rather than a conventional alpha-amino acid. That ring is why proline introduces kinks into polypeptide chains, and why it lands under a different customs heading from the amino acids sitting beside it on a price list. Physically it is a white to off-white crystalline powder, markedly hygroscopic, melting around 228 °C with decomposition and dissolving in water at roughly 162 g per 100 mL at 25 °C, making it one of the most soluble amino acids in this catalogue. Its dissociation constants are pKa 1.95 and 10.64 at 25 °C. Proline and its hydroxylated form, 4-hydroxyproline, together account for a large share of the residues in collagen; prolyl hydroxylase converts proline residues to hydroxyproline in an ascorbate-dependent step that stabilises the triple helix. This is why proline is formulated alongside glycine in collagen peptide blends. Bulk L-proline is made by microbial fermentation, industrially using mutagenised or metabolically engineered Corynebacterium glutamicum grown on glucose, so the material is non-animal in origin and supports vegan positioning without further qualification. Outside nutrition, L-proline is a well-established asymmetric organocatalyst in fine chemical synthesis and a routine component of cell culture media. Because proline deliquesces readily, Thovek packs it in moisture-barrier liners with a desiccant option and recommends tightly closed storage under cool, dry conditions - a handling note worth passing to warehouse teams before the first container lands. Grades run from Ph. Eur./USP/JP pharmaceutical through AJI food grade to cell-culture material with controlled endotoxin and bioburden. Every lot carries a batch Certificate of Analysis, SDS, fermentation-origin declaration and India-origin export documentation against the 29339900 tariff line.