Involved in the biosynthesis of terminal alkyne-containing amino acids such as L-propargylglycine (Pra) and L-beta-ethynylserine, that are produced as antibiotics by S.cattleya. Catalyzes gamma-elimination of chloride from 4-chloro-allyl-L-glycine (also named L-2-amino-4-chloropent-4-enoate), followed by an isomerization, to form the terminal-alkyne product L-propargylglycine. L-2-amino-4-chloropent-4-enoate = chloride + H(+) + L-propargylglycine Amino-acid metabolism. Antibiotic biosynthesis. Cells lacking this gene no longer produce detectable amounts of L-propargylglycine and L-beta-ethynylserine, that are terminal alkyne-containing amino acids produced by wild-type S.cattleya. They accumulate the intermediate 4-chloro-allyl-L-glycine. Belongs to the trans-sulfuration enzymes family. Truncated N-terminus.