– Enopeptin A, originally isolated from a culture broth of Streptomyces sp. RK-1051, is a depsipeptide antibiotic containing two unusual amino acids (N-methylalanine and 4-methylproline) and features a pentaenone side chain. It is effective against Gram-positive bacteria, including methicillin-resistant S. aureus (MIC = 25 μg/ml), and Gram-negative bacteria, including mutant forms of E. coli and P. aeruginosa (MICs = 200 μg/ml); however, it is not inhibitory to fungi.