L-Threonine-15N is primarily used in scientific research as a stable isotope-labeled compound. It serves as a tracer in metabolic studies, allowing researchers to track and analyze the pathways and mechanisms of nitrogen metabolism in biological systems. This labeled form of threonine is particularly valuable in nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, where it helps in elucidating protein structures and studying amino acid incorporation into proteins. Additionally, it is employed in nutritional research to investigate the role of threonine in animal and human diets, providing insights into its essential functions in growth, immune response, and gut health. Its use in stable isotope labeling also aids in the development of diagnostic tools and therapeutic strategies in medical research.