The incorporation of the stable isotope 15N into a molecule through labeling has numerous research applications. It is particularly useful in metabolic studies and protein research, where the nitrogen atoms in amino acids can be labeled with 15N. By monitoring 15N incorporation into the amino acids of a protein, researchers can study protein synthesis and turnover, providing valuable insights into biological systems. Moreover, 15N labeling has applications in environmental studies, where it is used to study nutrient cycling in ecosystems. By tracking 15N-labeled nutrients through an ecosystem, researchers can gain a deeper understanding of nutrient absorption and recycling by various organisms and ecological processes. In drug discovery and development, 15N labeling is used in metabolism studies. Labeling a drug molecule with 15N enables researchers to monitor its metabolic fate and understand how it is processed within the body. In summary, 15N labeling is an essential tool in various research fields, such as protein research, metabolic studies, and environmental science. By incorporating 15N into a molecule, researchers can track nitrogen atom fate in biological and ecological systems and study drug metabolism.