Cypemycin, isolated from the bacterium Streptomyces sp. OH-4156, is a peptide antibiotic, member of the linaridins, a class of posttranslationally modified ribosomally synthesized peptides. The enzyme decarboxylates and reduces the C-terminal L-cysteine residue, producing a reactive ethenethiol group that reacts with a dethiolated cysteine upstream to form an aminovinyl-methyl-cysteine loop that is important for the antibiotic activity of the mature peptide. Formerly EC 1.3.99.n3.
