D-Isoleucine is the D-enantiomer of the essential amino acid isoleucine, primarily utilized in scientific research and pharmaceutical applications due to its distinct biochemical properties compared to the natural L-form. In research laboratories, it is employed to study enantioselective interactions, protein folding, and metabolic pathways involving D-amino acids, which play roles in bacterial cell walls and certain neurological processes. In the pharmaceutical industry, it serves as a building block for synthesizing modified peptides, antibiotics, and other drugs where the D-configuration enhances stability, resistance to enzymatic degradation, or specific bioactivity. It is not typically used in dietary supplements or medical nutrition, as D-amino acids are poorly metabolized by human enzymes and lack the nutritional benefits of L-isoleucine.