L-Threonine

L-Threonine (CAS No.: 72-19-5) is an essential proteinogenic amino acid occurring naturally in the biologically active L-form and widely distributed in dietary proteins such as eggs, milk, and gelatin, as well as produced industrially via microbial fermentation for applications in food, pharmaceutical, and feed research. As a key component of cellular metabolism, L-threonine participates in protein biosynthesis and is catabolized primarily through threonine dehydrogenase–mediated pathways to generate glucogenic intermediates, including succinyl coenzyme A and pyruvate, thereby linking amino acid turnover to central carbon metabolism and energy homeostasis. In biomedical research, it is commonly used to investigate amino acid sensing, nutrient signaling pathways such as mTOR regulation, and metabolic adaptations associated with nutrient availability, with deficiency models demonstrating impaired growth, reduced food intake, and musculoskeletal abnormalities in animal systems. Although it does not function as a direct pharmacological inhibitor or receptor ligand, its modulatory effects on metabolic flux and cellular proliferation are routinely examined in vitro and in vivo, typically at concentrations ranging from micromolar to millimolar levels depending on experimental design. L-threonine is therefore widely utilized in cell culture optimization, metabolic profiling, and nutritional intervention studies, as well as in preclinical models assessing amino acid balance, protein synthesis, and metabolic disorders relevant to drug discovery and systems biology.