Propargylglycine is a non-proteinogenic amino acid found in a variety of organisms including Amanita mushrooms and the bacteria Streptomyces cattleya. It is a toxin that interferes with the metabolism of sulfur-containing amino acids via inhibition of cystathionine ó-lyase (also known as cystathionase or CSE).
Propargylglycine is a is non-proteinogenic amino acid that features an unusual terminal alkyne group. It is chemically related to ò-ethynylserine, with which it shares a biosynthetic pathway, and to cyanoalanine. Propargylglycine is useful in click chemistry applications.
Propargylglycine acts as an irreversible inhibitor of cystathionine ó-lyase (CSE), an enzyme that catalyzes the breakdown of cystathionine to cysteine and is involved in the endogenous production of hydrogen sulfide (H<sub>2</sub>S). It functions as a mechanism-based inactivator, forming a covalent adduct with the enzyme's pyridoxal 5'-phosphate (PLP) cofactor. Due to its inhibition of CSE, propargylglycine is widely used as a research tool to study the biological roles of H<sub>2</sub>S in processes such as vasodilation, inflammation, oxidative stress, and various disease models (e.g., hypertension, renal injury, myocardial protection, and hypoxic responses).
It also inhibits other PLP-dependent enzymes such as methionine ó-lyase (MGL) and alanine transaminase (ALT).