L-Threonine Manufacture Standards: FCC4,AJI92,USP26,EP4 L-ThreonineIndications and UsageThreonine (abbreviated as Thr or ... (2S,3S) and (2R,3R). However, the name L-threonine is used for one single enantiomer, (2S,3R)-2-amino ... which is rarely present in nature, is called L-allo-threonine. The two stereoisomers (2R,3S)- and (2R, ... away from moisture and strong light/heat. High Quality L-Threonine 99.0%