D-Propargylglycine is a non-proteinogenic amino acid derivative characterized by a propargyl group (-C≡CH) attached to the alpha-carbon of glycine. This structure incorporates both an amino acid backbone and a terminal alkyne functional group, making it a versatile chemical entity. Its primary and most significant application is in biochemical and pharmacological research as a mechanism-based, irreversible inhibitor of the enzyme cystathionine γ-lyase (CSE). CSE is a key enzyme in the endogenous production of hydrogen sulfide (H₂S). By inhibiting CSE, D-propargylglycine is extensively used as a research tool to study the physiological and pathological roles of H₂S in various systems, including cardiovascular function, inflammation, and neurotransmission. The propargyl group is crucial for its inhibitory activity. Beyond its role as a biochemical probe, the molecule serves as a valuable synthetic building block. The presence of both an amino group and a terminal alkyne allows it to participate in diverse chemical reactions, such as click chemistry via copper-catalyzed azide-alkyne cycloaddition (CuAAC), enabling its use in bioconjugation and the synthesis of more complex molecules for chemical biology.