“…DL-4-Azaleucine was first synthesized in 1963 as an analogue of leucine (24) and subsequently isolated as a metabolic product of Streptomyces neocaliberis (5). It is a potent growth inhibitor of Escherichia coli (20,24), Salmonella typhimurium (25), Pseudomonas mildenbergii (5), Proteus rettgeri (5), Sarcina lutea (5), Leuconostoc dextranicum (5), and blue-green algae (1). The toxicity of azaleucine has been associated with its incorporation into protein in place of leucine, resulting in inactive enzymes (4,20), and with its repression of the biosynthetic enzymes for leucine, isoleucine, and valine (6,20,28).…”