D-Citrulline is the D-enantiomer of the non-essential amino acid citrulline, primarily utilized as a specialty chemical in biochemical research, peptide synthesis, and pharmaceutical development. It serves as a chiral building block for creating enantiomerically pure compounds, enabling studies on enzyme stereospecificity, receptor interactions, and metabolic pathways. Unlike L-Citrulline, which is used in dietary supplements, D-Citrulline is employed in laboratory settings for its distinct chemical properties, including in the synthesis of modified peptides and as a probe in proteomics and drug discovery. Its role in investigating ammonia metabolism and urea cycle analogs also supports advanced research into metabolic disorders.